Abstract

In this theses , the sensitivity of porous silicon (PS) was developed to sense the temperature by deposition of graphene on Porous silicon (G/PS) by three different methods( drop casting ,welding process , candle coal) , which can be used in the application of thermal sensors (temperature sensors). Silicon wafer (n-type) with orientation (100) was used in this research, with a resistance of about (1-10) Ω.cm to prepare the porous silicon by the photoelectrochemical etching (PECE) by passing a current of density (J = 15mA / cm2) with a concentration of hydrofluoric solution (HF) by 20% after it was diluted with a high ethanol solution Purity and a time of (15 min). Where the structural, morphological, optical, chemical and electrical properties were studied by deviation (XRD), field emission scanning electron microscopy (FE-SEM),Atomic force microscopy (AFM), (EDX) test shows the components of the substrate, Optical properties (UV-Visible spectroscopy), fourier transform infrared (FTIR) spectrum and (I-V) characteristic . XRD showed a wide diffraction peak when the size of the crystal becomes nanometers, and the (FE-SEM) examination showed a clear picture of the surface porosity and graphene penetrating inside these nonporous. In addition, AFM show the roughness and morphology of surface for PS layer like sponge . While the absorbance show in two concentrations (100% - 50%) (1082 -1092) nm and energy gap was (1.58-1.78) ev respectively and FTIR test illustrated wide adsorption at 3439 cm-1 for (O-H), (C=O) at 1678 cm-1 and C=C at 1639 cm-1 .The results of thermal sensor obtained by examining (I-V) at room temperature 27C0 and high temperature 100C0 and the changing of current density were noted. The current-voltage measurement observed gradual increase in the current at a certain temperature limit for the three samples that were prepared by three deposition methods Drop casting method , welding process and candle coal. After continuing to increase the temperature with constant voltage, we notice a decrease in the current readings until the sample break down and the current becomes zero. It was found through thermal testing of the three samples that the drop casting deposition method is more sensitive to heat and more resist.

Abstract

The pure, Fe, Ag, Mn-doped and (Fe/Mn, Ag/Mn) co-doped copper sulfide nanostructures with high surface areas were synthesized by a hydrothermal technique using simple materials. All the samples were prepared and characterized by X-ray diffraction (XRD), Williamson – Hall analysis (W-H), Field-Emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), zeta potential, ultraviolet-visible spectroscopy (UV-vis), and Fouriertransform infrared spectroscopy (FTIR). The XRD patterns indicate that all CuS samples are in hexagonal covellite polycrystalline phases with estimated crystalline sizes of 25.14–11.03 nm. No impurity peaks are observed, indicating the high purity of the final products. The W-H method could be used to measure the lattice strain in the undoped and co-doped samples. It is clear that the values for crystallite size obtained from the W-H plot were higher than those obtained from the Scherrer relation calculation. FESEM measurements showed that the products at different magnifications are composed of microspheres, and the structures that resemble spheres are made up of tens to hundreds of selfassembled nanoplates, perfectly organized and oriented, which are thick at 26–177 nm. EDS spectroscopy was used to identify the existence of components in the prepared samples, the results demonstrating both the purity of the samples and the successful doped of Fe, Ag, and Mn in the CuS host structure. The zeta potential examination was used to estimate the size of the electrostatic potential of the suspension in the solvent. The zeta potential measurements showed that undoped and Fe, Ag doped, and (Ag/Mn) co-doped CuS have a surface charge electrically stable, while the surface charge of the Mn-doped, and (Fe/Mn) co-doped is weakened. Optical measurements indicated the absorbance of CuS samples was highly extended to the visible region in the range 200−600 nm, and this area is important for antibacterial activity. The calculated band gaps were 3.19–2.24 eV. The FTIR peaks indicate the successful preparation of CuS nanostructures. The antibacterial activities of pure CuS doped with Fe, Ag, Mn, and co-doped (Fe/Mn, Ag/Mn) against E. coli, S. aureus, and P. aeruginosa were evaluated by the inhibition zone method. All samples exhibited strong antibacterial activity against all strains. The highest level of inhibition against all strains was observed with a concentration of 4 mg/ml of copper sulfide. Among all the samples that were tested, (Ag/Mn) co-doped copper sulphide showed the highest antibacterial activity against both negative-gram and positive-gram bacteria.

Abstract

To develop sustainable photovoltaic materials in a competitive powergeneration market, a number of parameters, including cost, resource availability, and environmental constraints, must be taken into consideration in both material selection and processing. Cu2ZnSnS4 (CZTS) is an attractive option for Photovoltaic (PV) applications because, in addition to its material properties, which make it a suitable choice for PV applications, all of its constituent elements are abundant in the crust. This leaves us with the task of synthesizing such a compound in order to increase the quality and performance of devices made from CZTS thin films. A facile one-step hydrothermal method was utilized to prepare Cu2ZnSnS4 film using ethylenediaminetetracetic acid (EDTA) as a complex agent. The efficient Molybdenum oxide layer was also grown by the same step as preparing the Cu2ZnSnS4 film. In this study, the effects of zinc concentrations, copper concentrations, different pH values, and different preparation temperatures on the structural, optical, and electrical properties were studied. Also, Raman analysis and X-ray diffraction supported the creation of polycrystalline kesterite phase Cu2ZnSnS4 films with preferred orientation along (112) plane and showed that structure property alters with work conditions. The thicknesses of Cu2ZnSn4 film were about (1-2) µm. Interestingly, Field emission scanning electron microscopy (FE-SEM) revealed that surface morphology changes as work conditions change. UV-visible analysis showed high and broad absorbance spectra with high absorption coefficient values of more than 104 cm-1 in visible and infrared regions for all samples. The photoluminescence analysis demonstrated a single emission peak located at positions which is quite near to the band gap of ideal kesterite Cu2ZnSnS4 forall samples. Finally, Hall measurement showed that all samples were p-type semiconductors. Also presented that the optimum conditions for synthesizing high-quality CZTS film were (Copper/(Zinc+Tin)=0.79), (Zinc/Tin=1.2), (pH=9), and T=200 0C for 24h. Finally, the best heterojunction solar cell was made with Mo foil /MoO3/CZTS/ Zn0.35Cd0.65S/ZnO/Al configuration. A photovoltaic conversion efficiency of (2.21%) was attained under 100 mW/cm2 with an open-circuit voltage of (0.415) V, short-circuit current density of (14.3) mA/cm2 and a fill factor of (37.4%). The spectral response of CZTS- the based cell showed three response regions and the maximum was at 680 nm.

Abstract

Despite the remarkable and successful application of metallic orthopaedic surgery and bone replacement, there are main challenges of the long-term lively remains. Due to the poor osteoconductivity and dangers associated with surface corrosion and infections post-surgery, there is a related attention on improving the osteointegration of metallic implants with the surrounding tissues. In this study, bioactive nanocomposite coatings of bioceramics on metallic substrates (316L stainless steel substrates) were developed. Two methods of coating are adopted, electrophoretic deposition (EPD) and thermal spraying, to find the most appropriate method in terms of coating properties, attachment to the substrate, and the lowest cost. The EPD deposition method was adopted for three reasons: lower cost, better attachment to the substrate, and more stability for hydroxyapatite. In the present work, the chitosan was used as the organic part, acting as the matrix of the coating and enabling the coating to attach to the metallic substrates. Different types of ceramic fillers were investigated for the inorganic phases of the coatings, which were hydroxyapatite (HA) and titanium dioxide (TiO2). The major goal was to develop suitable EPD technology and understand the properties of nanocomposite HA / TiO2 coatings concerning the TiO2 concentration, to produce coatings with: adequate (i) homogeneity, (ii) attachment to the substrate, (iii) roughness, (iv) wettability and morphology, (v) electrochemical behaviour, (vi) bioactivity, and (vi) degradation behaviour. Other properties, such as antibacterial activity, were also analyzed. Different approaches were studied: substrate surfaces with different roughness (320-grit SiC grind, 800-grit SiC grind, and sandblasted surfaces); also, different deposition parameters were used (concentration of powders, applied voltage, and deposition time). Taguchi's approach was used to select the optimum conditions for deposition coatings. These conditions were 3 g/L, 50 V, and 1 min. The SEM and AFM analyses of HA/TiO2 nanocomposite coatings show the variation in the morphology as a consequence of different TiO2 concentrations. This appears in the reduction in the porosity and surface roughness of the coatings due to the addition of TiO2. The wettability measurements showed that all the coating surfaces are hydrophilic, with contact angle values ranging from 48.42° to 69.43°. XRD and EDS were used to investigate the composition and structure of the deposited coatings. The results proved that EPD did not affect the composition of the coating. To evaluate the bioactivity and formation of natural hydroxyapatite, all the coated samples were immersed in simulated body fluid (SBF). The results confirmed that all coatings showed good bioactivity and that hydroxyapatite formed on their surfaces after being immersed in (SBF). The results also proved that all coatings imparted corrosion protection to the substrate when evaluated via potentiostatic polarization curves by immersion in SBF, but the coating with a 75% concentration of TiO2 showed the best corrosion protection and a lower corrosion rate. The diffusion method was used for the assessment of antibacterials against two types of bacteria; Gram-negative Escherichia coli (E. coli), and Gram-positive Staphylococcus aureus (S. aureus). The samples exhibited good antibacterial activity against the Gram-negative type and excellent antibacterial activity against the positive type.

Abstract

Iraqi petroleum, especially from the Al-Ahdab, has a big problem resulting from its high percentage of heavy metals, high sulfur content ,and low API(American Petroleum Institute) leading to low specification of products. Furthermore, its ability to accelerate distillation tower is of great concern to the petroleum industry and the environment. The object of this study is to obtain light crude petroleum by eliminating or reducing these elements and obtaining outcomes that are as close to the criteria as possible. By using a novel magnetic ceramic filter synthesized by combining kaolin is low-cost environmentally friendly, with a low sintering temperature and palm frond in a 30% ratio with Co0.8Ni0.2Fe2O4 nanoparticles in a various weight ratios (5, 10, 15, and 20 wt%). In this study, CNF (Cobalt-Nickel ferrite) nanoparticles were synthesized using the sol-gel process. The effect of the nickel-substituted cobalt ferrite, heat treatment, and pH value was studied. After examining the microstructure, physical, mechanical, and magnetic properties of the CNF nanoparticles. Then, the specimen Co0.8Ni0.2Fe2O4 prepared at pH = 9 and treated with 1100 °C has the optimum properties particularly magnetic properties. It was selected to prepare magnetic ceramic filter. In this research investigated the addition effect of Co0.8Ni0.2Fe2O4 nanoparticles could change microstructure, physical, mechanical, and magnetic properties of the ceramic filters. The results show Field Emission Scanning Electron microscopy a homogeneous grain, porosity and bond microstructure together by a finer matrix without internal defects. The addition of Co0.8Ni0.2Fe2O4 in the ceramic filter may cause changes in the magnetic properties. The magnetization and coercivity increasing from (0. 0.215to 9.76emu/g) and (371.05 to1159.7Oe), respectively with increasing Co0.8Ni0.2Fe2O4 content. The addition of CNF nanoparticles will decrease the porosity and water absorption, due to CNF nanoparticles used as filler that close some pores. While compressive strength and diametrical strength increasing with increase CNF nanoparticles. API gravity of crude petroleum increase reach 32% after treated with magnetic ceramic filter. While decrease Sulfur content, Carbon residue, Asphaltenes content reach 2.8, 5.83, and 2.67, respectively. Removal efficiencies of Ni, Si, V, Ca, Na,Cr, Mg, and Mn was determined 72.53%, 96.37%, 54.32%, 89.58%, 92.10%, 75.55%, 77.17%, and100%, respectively. Reuse studies concluded that the magnetic ceramic filter can be reused up to three cycles repeatedly. As a result, heavy oil has been converted to the lightest petroleum obtainable. These filters will also become more popular because of their low preparation costs, ease of preparation, high adsorption capacity, and easy recycling features.

Abstract

Superconductor Materials have entered into many applications and advanced technological fields, due to their excellent properties characterized by zero resistance and expelling the external magnetic field. High-Temperature Superconductors (HTS) have become the focus of researchers and scientists that gives significant critical temperatures compared to traditional materials. This study focuses on preparing a series of High-Temperature Superconductor YBa2Cu3O7-δ (Y-123) oxide, by using the SolutionGelatin (Sol-gel) and Citrate Pyrolysis methods. In addition, studying the effect of the sintering time at (15 and 25) hours on its properties. The best (Y-123) sample was prepared by the sol-gel method using a sintering time of about 25 h, and it has the highest critical temperature (Tc= 91 K), according to the Resistance-Temperature test (R-T). In contrast, the best critical temperature (Tc) of the (Y-123) sample was about (Tc= 95 K) using a sintering time of 25 h, which was prepared in the Citrate Pyrolysis method. The final (Y-123) samples were analyzed by X-ray diffraction (XRD), which showed that all samples have an orthorhombic structure. And, the field emission-scanning electron microscopy (FE-SEM), showed that the (Y-123) samples consisted of plate-form grains. According to our results, we suggest this (Y-123) material is suitable for renewable energy applications.

Abstract

In this study, the layers of porous silicon (PS) produced from the n-type silicon with a (100) orientation and 0.1-100 Ω.cm resistance with the use of the approach of photoelectrochemical etching, the samples were anodized in a mixture solution of 48% HFc and 99% concentration C2H2OH, HFc concentration in the solution has been 20%. Morphology characteristics of the samples of PS prepared have been studied by different etching time(5,15,and 25min) of the value of the current density in to 20 mA/cm² , and imaged PS sample in the Scanning electron microscopy(SEM) and the Atomic force microscopy (AFM),there were showed rough silicon surface, with the increase in the process of the etching (i.e. the etchingtime) nucleates of the porous structure that results in increasing the surface area. As a result, the roughness of the surface increases, and it has been discovered that the PS’s porosity increases with the increase of the time of etching. The measurements of the X-ray diffraction (XRD) have confirmed the PS crystallinity nature. ZnO was prepared in two Methods. In the first, ZnO NPs were synthesized via laser ablation using a Q-switched Nd:YAG laser. YAG laser with a wavelength of 1064 nm and a constant 200 shots at various laser pulse energies ranging from 400 to 800 mJ, ZnO NPs deposition on PS by drop-casting. morphological properties for ZnO NPs/PS were studied by XRD ,SEM, and AFM The results show XRD studies revealed that as-synthesized ZnONPs are polycrystalline structure of the zinc oxide.For samples, the SEM image shows roughly spherical particles with some aggregation.UV spectroscopy was used to investigate the optical properties of ZnO NPs. Spectroscopy in the UV-Visible Range The peak absorption of ZnO NPs suspense in Methanol was found to be between 317 and 315 nm, according to the absorption spectra. Displays the PL spectra at room temperature for the samples ZnO NPs/PS produced photoluminescence bands Spectrum ZnO NPs/PS systems at about 501 nm. The second ZnO nanostructure was made using a hydrothermal method that involved zinc acetate dehydrate (Zn(CH3COO)2.2H2O) 0.35 g and citric acid monohydrate (C6H8O7H2O) 0.24 g, (NaOH 10 M) for 19 hours at 150°C, and then drop-casting ZnO nanostructures onto PS. morphological properties for ZnO nanosetructures /PS were studied by XRD ,SEM, and AFM the results show XRD studies revealed that the hexagonal as-wurtzite ZnO is in the diffraction patterns , SEM image shows ZnO NPs agglomerate at the top of the surface of PS and take on a spherical shape. UV was used to investigate the optical properties of ZnO nanostructures. Spectroscopy in the UV-Visible Range The peak absorption of ZnO NPs suspense in Methanol was found to be around 380 nm, and shows PL spectra excitation value of the (498-520) nm. From as a result of photodetector measurements The performance of ZnO NPs/PS photodetectors was improved over a wide range of wavelengths. From results of gas sensing, the effect of changing the operating temperature of NO2, NH3 gas sensors fabricated from prepared samples on the sensor's sensitivity, recovery time, and response time. the maximum sensitivity of a NO2 gas sensor made of ZnO NPs/PS (600mJ), and the hydrothermal method the maximum sensitivity of a NO2 gas sensor made of ZnO nanostructures/PS (25 minutes).

Abstract

In this work, has been improve the sensitivity porous silicon (PS) by deposited multiwall carbon nanotube with zinc oxide nanoparticles (MWCNTs-ZnO NPs) on (PS) that can be used in gas sensors application. n-type silicon wafer (100) orientation was used for preparing porous silicon (PS) layers by photo-electrochemical etching (PECE) method, with resistivity of silicon wafer of about 1.5-4Ω.cm. The etching solution is made from of hydrofluoric acid and high purity ethanol by electrolyte solution concentration HFc=40%. PS samples were prepared at different etching current densities 12, 24 and 30mA/cm2 , and etching time 10min. structural, morphological, chemical, and optical properties are studied by X-ray diffraction (XRD), atomic force microscopy (AFM), Transmission electron microscopy(TEM) , Field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR) spectroscopy, and photoluminescence (PL) measurements respectively. XRD analysis is appeared broad diffraction peak when the size of the crystal becomes inside nanometer. AFM images showed the PS layer had sponge like structure. And next step of the work was deposited (MWCNTs) on (PS) samples by using drop casting method (5 drops) at J=12,24,30 mA/cm2 with other preparation conditions fixed. Then mixed MWCNTs with ZnO NPs at a ratio (70%-30%) and deposited on PS sample of by using drop casting method (5 drops) at J=12, 24, 30 mA/cm2 , and etching time 10min. The TEM, FE-SEM, AFM ,XRD, Raman spectroscopy and FTIR are used for investigation of MWCNTs/PS properties. While the Raman test illustrated the G, D that spectrum peaks at1583 cm−1 and 1325 cm−1 respectively. While the FTIR examine was investigate the presence of Si-C, C=C, C-H, C-O bonds. the AFM result Depicted that the pore diameter and average roughness were increased after MWCNTs deposition . When contrasted to a PS surface, this causes the pore size to enlarge, increasing the surface roughness.. MWCNTs-ZnO/PS was obtained by FE-SEM, AFM, XRD,PL and the FTIR techniques. The sensitivity measurements were done for all samples at room temperature for different gases that best performance of the sensor when working at room temperature and thus to guarantee sufficient lifetime of the sensor and don’t more electrical power is required for operation. ,The results showed that the highest sensitivity of the samples was at MWCNTs-ZnO/PS , then MWCNTs/PS, and the lowest in PS samples ,the sensitivity for acetone gas was greater than other gases.

Abstract

In this thesis, a recent work of synthesis Perovskite Solar cells (PSCs) was presented. Including device design by using the spin coating technique to fabricate cells with structure (FTO/c-TiO2/mp-TiO2/MAPbI3/Spiro-OMeTAD/Au) through modifying the electron transport layers (ETLs) by using mixed solvents of γbutyrolactone (GBL) and dimethyl sulfoxide (DMSO). In addition, studying the properties of MAPbI3 by the addition of GBL into a chlorobenzene (CBZ) antisolvent solution and dripping it onto the perovskite layer. Herein, two types of additives are used with the perovskite cell in different concentrations to improve the performance of the cell by using the one-step deposition method (spin coating technique). In the first type, mixed solvent engineering of GBL: DMSO with different volume ratios (0:100%, 20:80%, 40:60%, and 60:40%) is used to modify the ETL/perovskite interface via wetting mp-TiO2 ETL. In the second type, a simple interface engineering at the perovskite/ hole transport layer (HTL) by utilizing a mixture of GBL as an additive solvent into CBZ as an anti-solvent with different volume ratios (0%, 0.5%, 1%, and 2%). The results are accomplished using FESEM, XRD, UV-Vis, and PL examinations, as well as electrical properties and stability of the PSC, showing the changes in the structural, optical, and morphological properties of perovskite thin films. Moreover, the results confirm the modified perovskite with 1% GBL additive in anti-solvent CBZ is optimal that revealing a pinholes-free surface, low charge recombination, and higher crystallinity as shown by XRD, FESEM, UV-Vis, and PL respectively. Consequently, the power conversion efficiency (PCE) of modified PSCs improved to 18.97% compared with the control device. Additionally, the modified devices were more stable in the air, maintaining 81% of their original PCE. Besides, the treated device by the wetting of mp-TiO2 with an optimal ratio of40%:60% of GBL: DMSO solvents produced a higher PCE of 18.72% as demonstrated in the statistics results of the photo voltaic (PV) parameters. This improvement could be attributed to the high quality of perovskite with large grain size, suppressed charge recombination, and without any residual PbI2 phase. Resulting in an increment in the hydrophobicity of the perovskite layer that raises the ambient stability of the corresponding PSCs as demonstrated in the stability measurements of the un-encapsulated devices maintained at room temperature (RT) with a relative humidity of 30% by measuring the contact-angle water droplets onto fabricated perovskite layers.

Abstract

In the present study, the porous silicon (PS) layers have prepared on the n-type silicon with an orientation (100) and resistivity (0.1-100) ohm.cm , photoelectrochemical etching cell approach was used. In this method, the samples were anodized within a mixture of hydrofluoric acid (HF) at a concentration of 48% and C2H2OH at a concentration of 99.99%, where the concentration of hydrofluoric acid in the solution was 20% with constant values for both current density (15mA/cm²) and etching time (15 min), the morphology characteristics of the produced samples were studied. Scanning Electron Microscopy (SEM) has displayed the rough silicon surface of PS samples. X-ray pattern examinations proved the crystallinity nature of the PS. Gold: Titanium dioxide nanoparticles were prepared via pulsed laser (Q-switched Nd:YAG) ablation method with two wavelengths ( 1064 and 532 nm) with different energies of the pulse laser ranging from 500 to 820 mJ and 500 shoots. Then, by the drop casting method, the nanoparticles of Au:TiO₂ were deposited on the PS. The NPs formation process was done with and without applied of a 500 mT of external magnetic field. When an external magnetic field was applied, a broad band occurred of Au:TiO₂ NPs as well as the absorption peak was higher at a quantum size effect. Examinations of transmission electron microscope (TEM) proved that the prepared Au:TiO₂ NPs possess spherical shapes with average size from 17 to 29 nmWhen a magnetic field is applied during the NPs preparation process, the plasma confinement increases, resulting in smaller nanoparticles and less NPs agglomeration. Study of many electrical parameters such as the barrier height (Φʙ) and ideal factor (n) of AL/Au:TiO₂ NPs/PS/Si/AL heterojunction determined with the Current-Voltage (I-V) measurements. We observed a decrease in electric current measurements for all samples manufactured in the presence of an external magnetic field using the laser ablation method. From the results of photodetector measurements, the effectiveness of Au:TiO2/PS photo-detectors has improved for a wide range of wavelengths. Ultimately, many of samples were used as devices of gas sensors (H2S and NO2) under several of operation temperature. The maximum sensitivity of Au:TiO2/PS (660mJ) gas sensor of H2S and NO2 gases. After applying magnetic field, the Au:TiO2 NPs /PS device prepared with laser energy of 500 mJ has higher sensitivity for H2S at each of 25 and 150oC. Whereas, the Au:TiO2 NPs /PS device prepared with laser energy of 660 mJ has higher sensitivity for NO2 at temperature around 100oC.

Abstract

High-Temperature Superconductors (HTS) have become a focus of attention for many researchers in the nanotechnology fields; therefore, many improvements have been made to products based on Superconducting materials to employ them in modern and future applications. This work aims to prepare Bi2PbSr2CaCu2O8+δ (Pb, Bi-2212) Superconductor material and study the effect of laser energy density on its properties, especially on the optical and electrical characteristics. This material is useful in optoelectronic device applications. In the first stage of preparation, a series of high-purity powders of Superconducting Bi2PbSr2CaCu2O8+δ (Pb, Bi-2212) oxide were synthesized using the solid-state reaction method (SSR), followed by a sufficient period of calcining and sintering process to investigate its properties such as critical temperature (Tc). Then, the resultant powders were ground and pressed into a disc-shaped (1.3×0.3) cm. The best (Pb, Bi-2212) samples prepared have achieved the highest critical Superconductor temperature of (Tc = 93 K), according to the Resistance-Temperature test (R-T), so this sample was chosen as the main target for the physical deposition process. The second stage comprises employing a pulsed laser deposition technique (PLD) for creating (Pb, Bi-2212) thin films using different laser energy densities (4.7, 6.3, 7.9, 9.5, 11.1) J/cm2 , which are produced on two various substrates such as Silicon (Si) and Glass (G). The (Pb, Bi-2212) samples were analyzed using the X-ray diffraction analysis (XRD), which was matched with the (JCPDS) database file; the crystallographic structure of all samples was shown to be an orthorhombic phase. Field emission-scanning electron microscopy analysis (FE-SEM) shows that the samples have spherical particles. The crystallite size of the (Pb, Bi-2212) material was measured from the FE-SEM images analysis (using the Image J software), which is equal to 42.8 nm for the (Pb, Bi-2212) target. And it increases from 41nm to 225 nm of the (Pb, Bi-2212)/Si film as laser energy density increases from 4.7 to 11.1 J/cm2 , also increases from 40 nm to 197 nm for (Pb, Bi2212)/G film. The optical energy gap of the (Pb, Bi-2212)/Si films decreases from 2.24 to 1.7 eV when the laser energy density increases and decreases from 3.6 to 2.1 eV for (Pb, Bi-2212)/G films. In addition, the optoelectronic characteristics of (Pb, Bi-2212)/Si PN-heterojunction photodetector were investigated. The electrical properties of the (Pb, Bi-2212)/Si PNheterojunction present, that the current transport mechanism is recombination-tunneling. The rectification factor decreased as laser energy density decreased.

Abstract

Poly methyl methacrylate was used as a base denture’s material originates by its distinct properties, despite that it had poor mechanical properties such as flexural strength and impact strength. In this work, stainless steel 316L (SS316L) wires with 0.8 mm diameter and 65 mm length were used to reinforce the PMMA samples and four wire surface modifications were conducted to investigate the possibility of improving the mechanical properties of the composite material. The surface modifications (treatments) involved: a scratching (mechanical treatment) of SS316L wires using silicon carbide powder for the treating periods 60, 90, 120, and 180 min, three electrodes anodization process by anodizing SS316L wires with AlCl3 solution at 20V applied voltage for the treating periods 15, 30, and 45 min, two electrodes anodization process by anodizing the wires with ethylene glycol solution and 5% of concentrated perchloric acid at 15V applied voltage for the periods 15, 20, 25, and 30 min, and coating the previously scratched wires with a layer of zinc via an electroplating process. A dilute acetic acid and Zinc Acetate solution was used for this process with an applied voltage of 5v for 60 minutes for all the scratched wires. All the prepared PMMA samples, having the dimensions of 65 × 10 × 3 mm3 , were reinforced by a single treated SS316L wire, besides preparing an unreinforced PMMA sample and a reinforced PMMA sample with untreated wire to accomplish the comparison. The treated wires were investigated using the SEM to see the effects of surface modifications and the treating time. SEM technique showed different morphological trace natures involving small dimensional grooves where their dimensions and concentration besides forming holes increased with increasing treating time. The largest dimensions recorded for the scratched samples were 60μm in length and 40μm in width. The SEM and EDX of the anodizing treatment showed forming metal oxides and pores, and the pores concentration was increased as the anodizing treatment time was increased. The SEM of the coated samples showed a presence of a good roughness in addition to forming zinc oxide. Impact and flexural strength tests were carried out for the PMMA samples that were reinforced with all treated wires. The results showed an improvement in the values of flexural strength that reached 113Mpa for a scratching time of 90min. The maximum flexural strength of the anodized samples was 93Mpa for the anodizing time of 15min using three electrodes anodization process, while the two electrodes anodization process for SS316L wire produced a reinforced PMMA sample of flexural strength of 100MPa for a treating time of 25min. as for samples reinforced with zinc electroplated SS316L wires showed enhancing in flexural strength test reach to 92 MPa. The impact strength of scratching samples showed the best result 42kJ/m2 for a treating time of 120 min. The coating also displayed a good impact strength of 41kJ/m2 for zinc-coated samples with a scratching time of 90 min. Most of the improvement was explained on the base of improving the adhesion between the wire and PMMA by modifying the surface of the wire. In other words, there were optimum values of treating time to give enhancements to the mechanical properties.

Abstract

In this study, the optical band gap of transparent conductive films, fluorine tin oxide (FTO) and indium tin oxide (ITO) as well as an opac silicon wafer (Si) are thoroughly investigated using two different methods; namely, Kubleka-Munk and Kummer. In particular, the utilized conductive films were selected with thickness of 300 nm for FTO and ITO, while an addition of 600 nm thickness was opted for FTO. Additionally, the employed Si wafer was investigated with two types, n-type and ptype. Concurrently, the optical characteristics of the addressed samples was investigated experimentally using ultraviolet–visible light spectroscopy (UV-Vis) and photoluminescence (PL) spectroscopy, while the structural features were studied using x-ray diffraction (XRD) technique. In detail, the XRD analysis revealed the occurrence of diffraction peaks at around 2θ=26.4°,33.6°,37.64°,51.4°,61.48°, and 63.4° which corresponded well to crystal structure of FTO (600 nm) planes (110), (101), (200), (211), (310), and (301), respectively. In the meanwhile, UV-Vis analysis indicated that the transparency of the tested FTO was decreased from 94 to 72 as the thickness increased from 300 to 600 nm. The optical band gap of the utilized FTO was found to be 3.34 eV, while the ITO optical band gap was found to be 4.90 eV. Subsequently, the PL analysis, excited using 250 nm He-Cd laser, revealed FTO with thickness of 300 nm exhibited an optical band gap of 3.34 eV; while ITO substrate demonstrated 4.9 eV optical band gap. As for the optical band gap of p-type and n-type Si, PL spectra elucidated a similar optical band gaps of 1.29 eV. In order to analyze the experimental results of the reflectivity method, the energy gap was calculated using two basic models. It was found that the absorption edge calculated from the reflectivity data at the start of the linear rise in the diffusive reflectance spectrum are consisted with the UV-Vis spectroscopy data obtained from methods 4, 5, and 6. However, the optical band gaps acquired using methods 1, 2, and 7 exhibited lower consistency as compared to those obtained using the reflectivity data.

Abstract

In the current work, un-doped and Cr -doped TiO2 nanorods NRs films was deposited using hydrothermal technique, on Fluorine doped Tin Oxide (FTO) substrate, with different doping ratios of Cr (0.5,1,5)wt%. Titanium botoxid was used as a precursor solution, while, chromium nitrate as a dopant in TiO2 NRs films. XRD for TiO2 NRs at different doping ratios illustrates the polycrystalline TiO2 with rutile and anatase phases. The preferred orientation along [001] for undoped sample converted to [101] direction with increasing doping ratio. In general, the intensity of the diffraction peaks decreases greatly with the increase of doping concentrations. The uniformly distributed nanorod arrays are shown in FE-SEM images from the top view and cross-section. The length of the undoped sample was 161.222 nm and the diameter of the nanorods was 52.811 nm as the doping ratio increased, the nanorods begin to bevel in the vertical direction.With increasing Cr doping ratios, in uv-vis the optical energy gap values decrease with increase Cr doping. Photoluminescence emission spectra. The measurements are carried out by excitation wavelength 270 nm (4.59 eV). Comparing the results shows that the energy band structure of TiO2 nanorods is independent of the excitation intensity. energy gap which very close to value obtained from Uv-Vis measurement, the PL intensity decrease after doping. Reflectance energy gap which very close to value obtained from Uv-Vis measurement D.C Measurements illustrate that samples TiO2 pure have one, activation energies. After doping two activation energies, the conductivity increases, and the activation energies decrease with increasing doping ratio. Prepare homojunction diode n-type TiO2 pure and p-type TiO2 with Cr doping, I-V characteristic prove it.

Abstract

In this research, the effect of adding woven carbon fiber treated with Para-amino benzoic acid (C7H7NO2) and Sodium hydroxide (NaOH) and coated by Beta Tri-calcium phosphate )β-TCP ( powder to the conventional poly methyl methacrylate (PMMA) has been studied. Two stages involved for the preparation of heat-cured acrylic denture composite, the 1st stage is the chemical treatment and coating of woven carbon fiber surface and the 2nd stage is the reinforcement of denture base material. To increase the surface roughness and improve the bonding among carbon fibers, calcium phosphate powders and the PMMA, the surface of carbon fiber has to be treated with Para-amino benzoic acid (PABA) and sodium hydroxide (NaOH) with various molarities: (0.10 M, 015 M, and 0.20 M). An immersion technique was used to coat the carbon fibers with a ceramic material (β-TCP) with various weight fractions (0.08, 0.10, and 0.12) wi to improve the black carbon fiber and strengthen some properties of the denture base. Also, to enhance bonding between fibers, and coating of calcium phosphate powder, polyvinyl alcohol (PVA) was mixed. Structural tests include (FTIR and FESEM). The resulting functional groups on the surface of carbon fiber before and after acid and alkali treatment were studied by FTIR. The morphology of woven carbon fiber (WCF) surface before and after the acid and alkali treatment, also measuring the diameter of pores on fibers, and showing the adhesion between β-TCP coating and fiber were carried out by FESEM. Mechanical tests include: impact strength (I.S) and flexural strength (F.S) is calculated using a Charpy impact test machine and a three-point bending test, respectively.The results manifested that the composites consist of WCF uncoated and treated with NaOH, the impact strength were higher than those composites consist of WCF uncoated and treated with PABA. Hybrid composites consist of WCF coated and treated with PABA at high concentrations recorded very high raises in impact strength compared with hybrid composites consists of WCF coated and treated with NaOH. Composites consist of WCF uncoated and treated PABA had highest flexural strength than the composites consist of WCF uncoated and treated with NaOH, also the hybrid composites contained WCF coated and treated with PABA recorded high values of flexural strength compared with the composites contained WCF coated and treated by NaOH. Through these results, denture base samples achieving remarkable improvement in some mechanical properties that represented by enhancement in both the impact and flexural strength.

Abstract

In this study, titanium dioxide (TiO2) films were prepared on the surface of FTO-glass and p-type Si (100) substrate by screen printing method , after preparing the TiO2 film , Barium titanate (BT) and barium strontium titanate (BST) films have been fabricated by hydrothermal technique on the surface of FTO-glass and p-type Si (100). The structural ,optical ,and electrical properties of the fabricated films were done. XRD displayed that the lattice system of TiO2, BT and BST films is tetragonal. The crystallite D size and strain were calculated by using the Williamson Hall plot of films. The morphology and distribution of the TiO2, BT and BST films were homogenous and in the form of nanorods of 0.91, 1.5 and 1.15 micron height , respectively, through the FE-SEM image. Results of UV-Vis characterization of TiO2, BT and BST film showed that the width of energy gap is respectively 3.4 (eV) , 2.9 (eV) and 3.1 (eV). The dielectric properties of TiO2, BT and BST films has been studied for different frequencies . The studied electrical properties of the prepared films manifested the possibility of using prepared films as a photodiode. The I-V characteristic was conducted in dark and illuminated conditions with a Xenon lamp. (J-V) characteristics were measured under the simulated Air Mass 1 conditions for a BT/Si and BST/Si photodiode. The nonideality factor (m) is 0.98 , 0.93 for The BT/Si and BST/Si film respectively .The BT/Si and BST/Si film begins to become more conductive when the illuminating power density increased, which qualifies the film for photovoltaic applications.

Abstract

In current research, cadmium sulfide doped with different ratio of (Ni, Mn, and Cu) elements was prepare by the hydrothermal method at 150 oC for 2 hours with concentrations from 1,2,3,4 and 5 Wt%. The effect of changing the dopant concentration on the structural, morphological, and optical properties of the produced samples have been study. The physical and chemical property of investigated all the prepared samples using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), UV-visible spectrophotometer, and Photoluminescence (PL). X-ray diffraction patterns confirmed the polycrystalline nature of pure CdS and (Ni, Mn, and Cu)-doped CdS thin films, exhibiting hexagonal wurtzite and cubic structure. Whereas the FE-SEM analysis was confirmed the success of the formation of flake-like for pure CdS and flower-like nanostructures for doped CdS samples structure. The topography was studied by atomic force microscopy. According to the results, the surface roughness increased when increasing the doping concentration. From UV-visible spectrophotometer with wavelengths varied from 300 to 1000 nm, the transmittance spectra were obtained; the films generated had a high transmittance in the visible region. The UV-visible spectra revealed that the energy band gap values decreased when increasing doping concentration. The results of UV-Vis spectroscopy agree with the conclusions of the PL study. Performance of the pure and (Ni, Mn, and Cu)-doped cadmium sulfide thin films was examined for the photocatalytic activity using organic dyes (methyl blue and methyl violet). The samples CdS with doping of (Ni, Mn, and Cu) showed increased photocatalytic activity. Where, the optimal maximum performance for CdS doped with Ni at 0.5% whose rate of degradation was 84.93 for methyl blue and 96.09 for methyl violet. The CdS doped with Mn at 0.4% whose rate of degradation was 84 for methyl blue and 98 for methyl violet. While, the rate of degradation was 89 for methyl blue and 97 for methyl violet for CdS doped with Cu at 0.5 %. The high photocatalytic activities of (Ni, Mn, and Cu) doped cadmium sulfide thin films were attributed to low energy bandgap and high surface area, under different levels of (Ni, Mn, and Cu) doping concertation as 1% to 5 % is step of 1% compared to pure sample.

Abstract

Perovskite solar cells (PSCs) are a modern class of solar cells, the aim of this study, it has been fabricated reduce graphene oxide/bismuth oxide (rGO/Bi2O3) nanocomposites to enhance the properties of mesoporous titanium dioxide (mp-TiO2) with improving performance of triple cation PSCs and the ambient air stability of PSCs at room temperature. This nanocomposite was added to the mp-TiO2 electron transport layer (ETL) with different volume ratios. A triple-cation formamidinium (FA)/methylammonium (MA)/Cesium (Cs) perovskite was used to fabricate high-performance perovskite solar cells (PSCs). The perovskite solar cells (PSCs) have been fabricated with an architecture of FTO/c-TiO2/mp-TiO2/perovskite/Spiro-OMeTAD/Au. The perovskite films were characterized using X-ray diffraction, field emission scanning electron microscope, UV-visible spectroscopy, and photoluminescence spectroscopy. The results show that the modified TiO2 has been improved the crystallinity of perovskite and enlarged perovskite grain as well as passivate grain boundaries. These improvements were beneficial for increasing the power conversion efficiency (PCE) of PSCs from 13.41% to 17.21% also the results show higher value of current density at short circuit point. It has been concluded the enhanced stability of the rGO/Bi2O3 has been achieved modifying PSCs is due to the stabilization of PVK film with larger grain size and higher crystallinity, which shows that the resistance of the modified perovskite layer to composition degradation is higher than that of unmodified films. The perovskite film with optimized 4% rGO/Bi2O3 revealed smoother surface with larger grain size and reduced grain boundaries.

Abstract

This study includes the preparation of iron oxide was coated with gelatin and gum Arabic, nanoparticles (NPs) of magnetic form had been prepared by using co – precipitation chemical method (Sol-gel). In order to reduce their toxicity and increase stability. The structural, optical, Morphology and chemical composition properties of the surface for prepared of coated and non-coated iron oxide NPs had been performed by X- ray diffraction (XRD), Energy dispersive x- ray (EDX), Fourier transfer infra-red spectrophotometer (FTIR), Zeta potential, and field emission scanning electron microscopic (FE-SEM). The X-ray diffraction analysis revealed the formation of a cubic crystal structure , iron oxide NPs coated with gelatin and iron oxide NPs coated with gum Arabic . It is indicated that the (NPs) was high purity and crystalline nature, also XRD analysis illustrated that both of gelatin and gum Arabic do not affect the crystalline nature and phase of the iron oxide nanoparticles this due to the absence or displacement of the diffraction peaks in the spectrum. Moreover, an increase in the average crystal size calculated by the Scherer’s equation for iron oxide was observed after coated with gelatin and gum Arabic about (8.9, 11.81 and 9.41 nm) respectively. FESEM images of iron oxide revealed the spherical nanoparticles formation in different size and distribution. The average particle size was about (27.8 nm). In the case of the UV-Vis test, the spectrum of Fe3O4 NPs shows continuous absorption 262 nm, While the absorption spectrum of Fe3O4 covered with gum Arabic shows a shift towards the longer wavelengths from 217nm to 249 nm. It was found that the energy gap value of the Fe3O4 NPs coated with gum Arabic and gelatin 2.5 eV, 2.8 eV, and 2.4 eV, respectively. Moreover, biological activity of coated and non-coated iron oxide NPs had been determined.by Removal of pollutant dye High and significant removal of Methylene blue pollutant dye (46 %) was observed with iron oxide NPs, while removal percentage were 34% and 22.6% incubation performed by iron oxide NPs coated with gelatin and gum Arabic within 72 hrs. Furthermore, antibacterial activity of fabricated nanoparticles was measured by well diffusion method against Escherichia coli and Staphylococcus aureus. Iron oxide NPs revealed high and significant inhibition zones of 27.5 and 30 mm, at 1000 μg/ml, against S. aureus and E. coli respectively, while coated iron oxide NPs with either gelatin or gum Arabic revealed low antibacterial activity against both examined bacteria even when used at 1000 μg/ml. On the other hand, the hemolysis activity of fabricated NPs is increase whenever concentrations increased. Hemolysis percentages were 69.76% and 50.98% for iron oxide NPs and iron oxide NPs coated with gum Arabic at concentration of 250 μg/ml, while lowest hemolysis percentage (17.45) was observed with iron oxide NPs coated with gelatin at the same concentration. Finally, cytotoxic activity was estimated against MCF- 7 cell line and normal cell line WRL68 by MTT assay. Significant and viability of MCF- 7 was 65.1% when 400 μg/ml of iron oxide NPs was examined, while the viability of WRL68 was 75.03%. Iron oxide NPs coated with gum Arabic revealed significant and lowest MCF-7 and WRL68 viability of 69.90% and 80.05 %, when applied at 400 μg/ml, iron oxide NPs coated with gelatin and examined at the same concentration show significant and lowest viability of 65.28% and 78.36 % respectively.

Abstract

In this work Porous silicon (PS) has been prepared from n-type Silicon via photo-electrochemical etching (PECE) technique with different etching time 5, 10, 15, 20, 25 min., fixed current density 10 mA/cm2, and fixed HFC 18%. Structural, morphological, chemical, electrical and optical properties of samples have been investigated. Magnesium Oxide nanoparticles (MgO NPs) have been prepared by the Laser pulse ablation technique via using Nd:YAG laser (Q-switching) of 1064 nm wavelength and 100 pulses of different energies 500, 600, 700,800, and 900mJ). Drop casting method has been adopted to deposit MgO NPs on PS samples. Structural, morphological, chemical, electrical and optical properties of samples have been investigated. The MgO NPs/PS characteristics were investigated via XRD, SEM, AFM, FTIR, the preparation samples offer MgO NPs with a bright spot of MgO NPs inside PS. MgO NPs/PS achieving remarkable improvement in photodetector measurements, that represented by enhancement in both of the responsivity and quantum efficiency. Therefore, MgO NPs/PS can be proposed as a photodetector candidate that operated over broadband spectral of wavelength. Furthermore, PS/n-Si and MgO NPs/PS have been explored as sensor through studying its performance for the humidity detection and temperature detection respectively. The experimental setup of humidity and temperature detection consists of resistance and capacitance that used for registering the response signals with a fixed frequency 10 KHz. MgO NPs/PS shows in average good detection performance.

Abstract

The graphene oxide (GO) nanosheets have been prepared by the electrochemical exfoliation method, which represents a simple and cheap technique. An acidic solution consisting of the following acids (H2SO4 , HCl, CH3COOH , H2O2 , HNO3) with pH = 4 was used for the purpose of peeling graphite rodes and producing few layers GO nanosheets (nanoparticles) and multilayers GO ≈ nanosheets (microparticles). The structural, spectral, and morphological properties of the synthesis GO nanosheets were characterized by using X-ray diffraction (XRD), Raman, Fourier-transform infrared spectrum (FTIR), Ultraviolet–visible (UV-Vis), field emission-scanning electron microscope (FE-SEM) techniques. As well as to measure the stability and mobility by Zeta potential. The XRD has been used to calculate the crystalline size and number of layers. Raman spectra of few layers and multilayers GO nanosheets showed three peaks D, G and 2D. The FTIR of few and multilayers GO nanosheets showed the oxygen-containing functional groups. The UV-Vis absorption spectrum of a few layers and multilayers GO nanosheets shows two peaks, belong to the electronic transitions π→π*, and n→π*, respectively. The FE-SEM shows the morphology of few layers GO nanosheets, which refers that the nanomaterial takes the sheet structure. While FE-SEM of multilayers GO nanosheets shows the accumulation of layers in a wavy form. Zeta potential analysis shows good stability of few layers GO nanosheets greater than the multilayers GO nanosheets The cell viability test showed that the few layers GO nanosheets have high killing rates for E. coli bacteria, while the killing rates of multilayers GO nanosheets were low.. The results confirmed that the few layers can be considered as anti-biofilm and anti-bacterial adhesion, while the multilayers did not have that effect. Hemolysis test confirmed that the few layers GO nanosheets were anti-hemolysis in acceptable proportions while the multilayers GO nanosheets cause hemolysis.

Abstract

Poly methyl methacrylate PMMA is the base material utilized in dentistry as denture base. But the material has weak mechanical properties when it is employed alone as it is broken at parts through an accident. So, the improvement of the strength of this material is very important. This study included the preparation of acrylic denture base layered composite by reinforcing the denture base material PMMA coated and uncoated carbon fibers CF (woven or chopped). The coating materials were Aluminum oxide Al2O3 and Tricalcium phosphate TCP powders which were used by dipping technique to get better aesthetic with hide a black carbon fibers color. To improve the contact between carbon fibers and coating material powders, the surface of CF was treated with Para amino benzoic acid C7H7NO2 and poly vinyl alcohol PVA. The mechanical tests through this study included impact strength and flexural strength. Also water absorption for specific samples, toxicity of carbon fibers, Al2O3 and TCP powders were studied. The effect of alkaline on impact strength for control and composite samples was studied. Surface morphology of the coating layer was examined by field emission scanning electron microscope FESEM. Results showed that, samples reinforced with uncoated (woven or chopped) CF had high impact and flexural strength, but still had a bad aesthetic. Samples prepared by coated carbon fibers with Al2O3 or TCP had high impact strength values compared to control sample, while flexural strength value had decreased. Impact and flexural strength values for samples prepared by coated CF with TCP were higher than Al2O3 due to the hardness and high fracture strength of TCP particles. Good aesthetic, impact and flexural strength were increased together in samples when PVA increased and chopped fibers amount decreased. Results also showed that the immersion of samples in NaOH solution had positive effect on impact strength. A separation of serum with coagulants was detected at tube containing carbon fibers immersed in blood. This test gave information about toxic property of carbon fibers. So, carbon fibers were incorporated in PMMA as a layer in the middle of acrylic resin.

Abstract

In this study, we report for the first time the preparation and characterization of silver sulfide (Ag2S) nanoparticles NPs by one-step laser ablation of silver target in thiourea aqueous solution. The effect of laser fluence on the crystal structure, morphology, size and elemental composition of Ag2S NPs was investigated. X-ray diffraction XRD results show the Ag2S nanoparticles are crystalline with monoclinic phase and the laser fluence affects the crystalinity of the synthesised nanoparticles. The optical energy gap decreases from 2.2 to 1.6eV as laser fluence increases from 2.38 to 6.77Jcm-2. Transmission electron microscope TEM investigation confirms the formation of spherical Ag2S nanoparticles and nanosheets morphologies and the particle size is found to increase from 30 to 65nm when the laser fluence increases from 2.38 to 6.77Jcm-2. laser ablation technique was also employed to synthesize monodisperse silver sulfide Ag2S nanoparticles NPs by laser ablation of silver target in the thiourea aqueous solution with cationic cetyl trimethylammonium bromide (CTAB) surfactant. The effect of CTAB surfactant on the structural, morphology, optical and elemental composition of Ag2S NPs was examined using x-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive x-ray (EDX) and UV-Vis spectroscopy. The optical properties results show that the optical absorption decreases and the optical energy gap of α-Ag2S increases from 1.5 to 2eV after adding CTAB surfactant to the thiourea solution. X-ray diffraction results reveal that the synthesized Ag2S NPs are polycrystalline with monoclinic structure and the crystallinity quality was improved and preferred orientation along (112) plane was observed after adding CTAB. The optoelectronic properties namely, dark current-voltage, illuminated current-voltage and spectral responsivity of α-Ag2S/p-Si photodetector are studied. The best photodetector was fabricated with laser fluence of 3.9J/cm2 in the presence of CTAB. The maximum responsivity was 1.85A/W at λ=460nm under bias of 3V. The TEM investigation confirms formation of highly monodisperse Ag2S NPs with pure spherical shape after adding CTAB. Finally, laser ablation technique was also employed to synthesis of Ag2S nanotubes (NTs) by laser ablation of silver target in Thiourea (Tu) aqueous solution. The effect of laser fluence on the crystal structure, morphology, size and elemental composition of Ag2S NTs were investigated. X-ray diffraction (XRD) results show that the Ag2S NTs are crystalline with monoclinic phase. The optical energy gap of Ag2S NTs is around 1.6 eV at fluence 4.7Jcm-2. Transmission electron microscope TEM investigation reveals the formation of NTs Ag2S morphologies with the diameter of 26-30 nm and lengths of 200-400 nm.

Abstract

In this work, un-doped, Mn and Ni-doped TiO2 nanorods (NRs) arrays films were successfully prepared by hydrothermal method, on (Fluorine doped Tin Oxide) FTO substrate, at different doping ratios of both dopants Mn and Ni (x= 0, 0.025, 0.05, 0.075 and 0.1). Tetraisopropoxide (TTIP) was used as a precursor solution, while, manganese acetate and nickel chloride as a dopant in TiO2 NRs films. XRD for TiO2 NRs at different doping ratios illustrates the pure rutile phase. The preferred orientation along [001] for pure sample converted to [101] direction with increasing doping ratio. The sharp peaks behavior for (002) are compared with the broadening of other peaks. Lattice constants increases with increasing doping ratio. FESEM images, from top and cross-view, show the uniformly distributed nanorods arrays. The above tips of the nanorods were in spherical shapes. 1950 nm length and 180 nm diameter for the pure sample and nanorods length decreased and their diameters increases with increasing doping ratio. The nanorods start to bevels from its vertical direction after doping with both dopants. The optical energy gap values decreases with increasing doping ratios with the both dopants. D.C Measurements illustrate that all samples have two activation energies. The conductivity increases and the activation energies decreases with increasing doping ratio with both dopants. All samples were n-type due to oxygen vacancies. The charge carrier concentration increases from 3.03×1017 cm-3 to 9.63×1017 cm-3 for 0.1 Mn ratio and to 1.07×1018 cm-3 for Ni doped, while, the carrier mobility decreased with increasing doping ratio. The magnetic property of TiO2 nanorods array films was measured by Vibrating Sample Magnetometer using very low paramagnetic, with no hysteresis of the un-doped sample. This was done with small hysteresis loops in all samples, in addition, to increase the susceptibility with increasing doping ratio.

Abstract

In this work TiO2 nanorod arrays films were prepared on fluorine tin oxide (FTO) substrate using hydrothermal technique, which is fast reaction velocity, simple and inexpensive technique. The growth parameters (reaction time and precursor content) have been considered in this study to specify the optimum condition. Electrical, Structural and optical properties of TiO2 films were investigated and analyzed extensively with different conditions. Structure and surface morphology of TiO2 nanorod array were characterized by X-ray diffraction and Field Emission Scanning Electron Microscopy measurements. Preparing TiO2 nanorod array films at different growth time of (3,4and 5) hours at constant precursor content (0.225 mL), also for different precursor content of (0.225, 0.4 and 0.5) mL at constant growth time (5) hours was achieved. X-ray analysis has confirmed the formation of rutile TiO2 nanorod and the nanorods were oriented in the [001] direction with grown axis perpendicular to the FTO substrate. The crystallinty of the film was enhanced when the growth time increased from 3 to 5 hours. The film with different precursor content showed well crystallized. FESEM measurements showed that the shape of the nanorods was tetragonal and the morphology (density, length and diameter) of the nanorods can be adjusted by varying the growth time and precursor content. The optical properties of TiO2 nanorod array were studied such as transmittance, absorption coefficient and energy gap for different growth time and various precursor contents. The optical energy band gap decreased from (3.5 to 3.1) eV with increasing reaction time. The optical energy band gap changed from (3.1 to 3.01) eV with various precursor content. The conductivity increased with increasing reaction time from (3-5) hours and precursor content. Hall measurements indicated that the TiO2 nanorod array is n- type semiconductors for the different parameters. Highly ordered vertically aligned TiO2 nanorod could be obtained at suitable conditions (TiCl4:0.4 mL, 5 hours). Dye-sensitized solar cell (DSSC) made with the optimized nanorod arrays employed as photoanod reached an overall photoelectric conversion efficiency of 2.15%. The effect of multiple growth cycles of TiO2 nanorod array on the DSSC performances was studied.

Abstract

In this work titanium dioxide (TiO2), iron oxide (Fe2O3) and indium oxide (In2O3) nanopowders were prepared by a hydrothermal technique. The TiO2 was mixed separately with Fe2O3, In2O3 and both mixtures were used to prepare three composite nanopowders (TiO2-Fe2O3, TiO2-In2O3 and TiO2-Fe2O3-In2O3) at (1:1, 1:1 and 1:1:1 mole) respectively (the optimum conditions at 400˚C (annealing temperatures, concentration) were determined. The nanopowders were investigated and analyzed at different parameters). Structure and surface morphology of powders were characterized by X-ray diffraction (XRD), Atomic Force Microscope (AFM), Scanning Electron Microscopy (SEM), Field Emission Scanning Electron Microscopy(FESEM) and FT-IR and UV-Visible measurements. Optimum condition of XRD for TiO2 powders annealed at (200, 400, 600 and 800◦C) for 120 min showed the formation of a tetragonal phase of powders with high intensity of plane (110). The lattice constants (a) and (c) increase with the increase of annealing temperature. The results of atomic force microscopy indicated an increase in grain size of TiO2 with increasing of annealing temperatures from 69.40 to 92.87 nm. The grain size decreased with addition of Fe2O3 or In2O3 to the TiO2 to reach 58.23nm and 75.59 nm respectively. The optical properties (absorption) of TiO2 nanopowders and its composites, its show that the degree of absorbance decreased with the addition of both metallic oxides (Fe2O3 and In2O3). The energy gap decreased with the increase of annealing temperature and increase in crystalline size according to quantum conferment. According to theoretical study by Gaussian program, there is an increase in both of bonding lengths and angles (TiO2 molecule) from 1.7100 Ǻ to average value 1.7193 Ǻ, 1.7456 Ǻ or 1.8245 when Fe2O3 was added, In2O3 or both of them respectively. The results of antibacterial activity for TiO2 and its composites with two types of bacteria Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aurous), showed an increase in activity with increase concentration of TiO2 and annealing temperature. It was observed that the composites were more effective in inhibiting a range of bacterial growth.

Abstract

In this project, Polyaniline (PANI) was prepared by chemical oxidative polymerization of aniline monomers as emeraldine salt form. The Cadmium sulfide (CdS) powder was prepared by using sol–gel method. Polyaniline-CdS nanocomposites have been prepared via same method of polyaniline preparation and different weight percentages of CdS (10-50 wt%) were added. Structural, optical, electrical properties and their applications of PANI, CdS nanoparticles and PANI-CdS nanocomposites were investigated. X-ray diffraction showed that the peaks of emeraldine salt polyaniline powder were located at 2θ = 21.5o , 25.7o and 28.1o which indicated polycrystalline polyaniline and the peaks of CdS powder were located at 2θ = 26.69, which indicated CdS coincides with hexagonal structure, 2θ = 47.47 which refered to CdS with hexagonal and cubic structures. The XRD pattern of PANI-CdS (10-50 wt %) composites exhibited the peaks of PANI and CdS together that’s indicated to interconnection between them. From UV-VIS measurements the optical band gap was decreased from 3.95 eV for 10 wt% to 3.65 eV for 50 wt% with increasing of CdS content. The SEM and AFM investigations showed that there was a uniform distribution for CdS nanoparticles in the PANI matrix. From the electrical study, the obtained resistivity of p-type PANI and n-type CdS films were found to be 0.02×10-2 and 5×106 Ω.cm respectively and this study exhibited the effect of crystallite size and high resistivity of CdS on the resistivity of nanocomposits. Emeraldine salt PANI, CdS and PANI-CdS nanocomposites were investigated as gas sensors. From this investigation, the sensitivity of PANI-CdS nanocomposits for NO2 gas increased with the increasing of operation temperature and the optimum sensitivity was obtained at 200oC. The sensitivity at best temperature (200oC) was increased from 240% for 10 wt% to 847% for 50 wt% with the increasing of CdS contents and the response time was decreased from 16 s for 10 wt% to 11 s for 50 wt%, these results refered to that the PANI-CdS nanocomposites have excellent sensors for NO2 gas as compared with pure PANI and pure CdS.

Abstract

This work involves a comparative spectral study for K2CrO4 and K2Cr2O7 using UV-Visible spectroscopy at different parameters such; K2CrO4 or K2Cr2O7 with H2O (different molarities), K2CrO4 or K2Cr2O7 with H2O and HCl (different pH values by increasing acidic solution), K2CrO4 or K2Cr2O7 with H2O and NaOH (different pH value by increasing alkaline solution). The amount of HCl dilute solution has been calculated that was added to change K2CrO4 to K2Cr2O7 and that observed by UV-Visible spectroscopy and pH-meter to get the absorption spectrum and pH values of K2Cr2O7 solution. The vibration modes (stretching or bending) of K2CrO4 and K2Cr2O7 powders have been studied by using FTIR spectroscopy. In this work also, a structure and surface morphology of K2CrO4 and K2Cr2O7 by XRD and AFM have been studied .

Abstract

In this project In2O3, ITO/ Si gas sensor were fabricated by an efficient and size – controlled. Many parameters have been study to proved the optimum conditions,(annealing temperatures, and doping concentration). Structural, optical and electrical properties of In2O3 thin films were investigated and analyzed extensively under different conditions. Structure and surface morphology of In2O3 thin films were characterized by X-ray diffraction. Atomic Force Microscope and Scanning Electron Microscopy measurements. Annealing was in air at different temperatures of (300,400,500) ̊ C and at constant time (60 min); the XRD technique that showed these films is polycrystalline structure with a preferred orientation of (222),( 440),(400) the best orientation plain is (222). These been found crystalline size increases with increasing annealing temperature and decrease with increasing doping concentration. The optical properties of In2O3, ITO thin films were studied such as transmissions, extinction coefficient, absorption coefficient and optical energy gap .The transmittance was measured in the wavelength range from(300nm to 900 nm) for all the films was highly transparent (greater than 85%). The optical energy band gap was increased with the annealing temperature in range from (3 to 4.9) eV, and increase with doping concentration in range from (3.9 to 4.15) eV. The electrical properties for In2O3 ,ITO thin films include D.C electrical conductivity and Hall effect which shows that the type of films is (n- type), and the film has two activation energies for pure and doped films in the rang (305-355)K, the resistivity decreases with increased annealing temperature. And resistivity increase with doping concentration at 8wt%. The sensitivity toward NH3, NO2 gas has been measured.In2O3 doped with (Sn) has higher sensitivity than that of pure for NH3, The sensitivity toward, NO2 gas has been measured, where In2O3 doped with (Sn) has higher sensitivity to NO2than to NH3.

Abstract

In this work preparation, and characterization of Silver and Tellurium nanoparticles were they synthesized by pulsed (Q-switched, 1064 or 532 nm doubled frequency-Nd: YAG) laser ablation of silver and Tellurium dioxide which cut into 10 mm x10 mm , cleaned and then immersed in double distilled and deionized water as a depth of 8mm, without any chemical additives. Different techniques such as X-ray Diffraction (XRD), UV-Vis spectrophotometer, Scanning Electron Microscopy (SEM) and Atomic Force Microscope (AFM) were used to study the structural and morphological properties of Ag and TeO2 nanoparticles. The effect of laser parameters such as laser energy, number of pulses and wavelength on the properties of nanoparticles were studied. It has been observed that laser energy, wavelength and number of laser pulses have a control over the size of the nanoparticles. The increasing of laser energy and number of pulses shows a clear blue shift in the absorption peak of fabricated nanoparticles indicating that the average size of the particles decreases with increasing of laser energy and number of pulses. Ablation for a longer period reduces the average size of nanoparticles which is attributed to the re-ablation of fabricated nanoparticles. The concentration of ablated Ag and TeO2 NPs with different numbers of laser pulses was obtained via Atomic Absorption Spectrometer (AAS); however it was found that the concentration of NPs increases linearly when the number of laser pulses increases. The average particle size was measured by scanning electron microscope and it was found to be between 166 nm to 151.8 nm for Ag NPs and 38 nm to 42 nm for TeO2 NPs. The relation between the ablation efficiency and wavelength varies with laser fluence and it can be noticed that the ablation efficiency at 532 nm has higher value at low fluence, while the ablation efficiency at 1064 nm has higher value at high fluence. These findings will be discussed in terms of the self-absorptions of the incident laser light by colloidal particles. The morphology of nanoparticles was studied as a function of laser wavelength and it's found that the average roughness varies with laser wavelength. Also the antibacterial effect of synthesized silver and TeO2 NPs was studied against four pathogens namely S. mutnas, S. aureus, P. mirabilis and E. cloacae. The activities of nanoparticles against the different bacteria were compared with the activities of four antibiotics such as amoxicillin, streptomycin, chloramphenicol and penicillin. It was found that the inhibition zone of bacteria by TeO2 nanoparticles has comparable results with antibiotics while Ag nanoparticles do not show such activity.

Abstract

Intense pulsed light, commonly abbreviated as IPL, is a technology used by cosmetic institutions and medical practitioners to perform various skin treatments. The technology utilizes Xe flash lamps to produce intense pulses of polychromatic and incoherent light, and to deliver them directly to target skin chromophores. The modifiability of several parameters; such as, wavelength, fluence, pulse duration, and pulse delay is of a great advantage for IPLs. In this study, the theory of the Xe flash lamp system was analyzed in order to design a flash lamp system. In addition, some experimental trials on different pulse durations and energies were carried out. Also, various flash lamp driving circuits were built up and tested on various Xe flash lamps. This was achieved by constructing a single and multiple-mesh pulse forming networks; using different types and values of inductance and capacitance circuits. The current discharge profile through the Xe flash lamp was measured by either an AT-C403 current probe or inserting a 70 mΩ resistor in series with the lamp. The output of the flash light was detected by using a reversed biased Si-photodiode. All optical and electrical measurements were recorded and stored on a digital storage oscilloscope. The results obtained showed a light pulse profile follows the exciting current pulse, meaning that the light pulse length is usually equal or slightly shorter than the current pulse duration. Any increase in the current pulse duration has led to an increasing of the pulsed light linearly.

Abstract

This study includes two steps for the preparation of acrylic denture base composite. The first step is carbon fibers coating and the second step is the reinforcement of denture base material. Sol-gel technique has been used to coat carbon fibers with calcium phosphate to improve the esthetic of black carbon fibers as it's biocompatible. To improve bonding between carbon fibers and prepared calcium phosphate powders, the surface of carbon fibers has been treated with para-aminobenzoic acid. The mechanical tests in this study include: (impact strength, flexural strength and surface hardness). According to the results obtained in this study, the mechanical properties of denture base resin have been considerably enhanced by reinforcement with uncoated and coated carbon fibers. The structural tests include: (SEM, XRD, AFM and FTIR). The morphology of the coating layers has been examined by scanning electron microscope (SEM). The crystallized phase composition of coatings has been identified by x-ray diffractometry (XRD). The grain size of dried and heat treated calcium phosphate coat has been estimated by atomic force microscope (AFM) and fourier transform ــ infrared spectroscopy (FTIR) analysis which support and verify the x-ray diffraction findings.

Abstract

During this research two types of supercapacitors (SC) were fabricated, tested and analyzed. The main objective was to use as possible as environmentally friendly, clean and natural materials for the SC electrodes, electrolytes and separators. The first type was a (7.5×2.5 cm2) tablet SC consisted of a multi-layer graphene (MLG); as the electrode material, prepared by mixing graphene powder with water/acetone mixture, then the solution deposited on metal foils (aluminum and copper) by chemical spray technique with two different thicknesses. The electrolytes were used is (lemon juice, table salt dissolved in water, and distilled water). The separators were commercial materials; PTFE polymer and cellulose based parchment paper (PP), as these separators are commercial; their dielectric constant has been calculated. The assembled SC were tested and measured their capacitance by LCR meter, the voltage across their electrodes were measured by digital multi-meter, the structural properties were tested by X-ray diffraction (XRD) for the MLG deposited on Al and Cu foils. As from the results, the highest measured capacitance was found to be (235.1 μF) for the (1.5 𝜇m) MLG deposited on Cu foil with the water and salt electrolyte and PP separator. Almost all the assembled SC had a good voltage readings (without charging it) despite its small dimensions. The XRD spectra showed that the structure of the MLG films deposited on Cu and Al is crystalline with orientation in the (002) direction.The second type of the fabricated SC; is a cell SC, Three types of plastic cases were used. In this type of design the electrode and electrolyte materials were mixed together and a solution formed. The electrode material was a graphene powder of different weights mixed with different volumes of electrolytes (which were: lemon juice, apple vinegar, H2SO4 and HNO3), and the separators used were PTFE and PP. Charging circuit was set, the cell SC charged with different charging rates and the voltage window was determined for each cell with different electrode/electrolyte/separator combination. Three of the fabricated cell SC were discharged through 0.5V LED light. The discharging rates were regular and the best was (1.22 volts discharged in 26 minutes). The capacitance, maximum energy and maximum power of the discharged SC were calculated. The mixed solutions were tested by XRD, its spectra showed high crystallinity for the graphene with two distinct peaks at (002) and (004) directions. The surface microscopy done by scanning electron microscope (SEM).

Abstract

In this work, colloidal SnO2 nanoparticles were prepared by using laser ablation of tin target immersed in different solvents (double deionized water, methanol and ethanol) without the use of any chemical/surfactant. This method is a promising technique for the fabrication of various nanomaterials and simply controlling the experimental parameters. The effects of solvents, laser fluence and number of pulses on the morphology, chemical, optical and electrical properties, of the synthesized nanoparticles were studied. X-ray diffraction shows that the structure of SnO2 NPs film is polycrystalline with preferential orientation in the (101) direction. Morphological properties were observed by TEM for particle size and shape. The SnO2 particles had an almost irregular shape with a mean diameter in water between 12 to 20 nm. Other solvents showed much larger particles with almost spherical shape. Particle size of SnO2 NPs observed by AFM images as a film deposited on glass slides, showed good agreement with the TEM results. The Fourier transform infrared spectroscopy (FTIR) spectrum showed a band in the range of 600–700 cm-1, assigned to Sn–O antisymmetric vibrations. The UV–Visible absorption spectra refer to sharp absorptions in the ultraviolet (UV) region. An increase in absorption peaks with the reduction in particles size was noted. The behavior of the UV–Visible spectra associated with the SnO2 nanoparticles was studied as a function of laser fluence, number of pulses and solvents. The optical band gap of SnO2 nanoparticles suspensions was between 4.14 to 4.32 eV in water solution, 4.12 to 4.26 eV in methanol solution and 4 to 4.13 eV in ethanol solution as when using different laser fluence and different number laser pulses. Hall Effect measurement of the SnO2 NPs suspensions prepared in different solvents showed them as n-type. Hall coefficient sign has not been changed with solvent type when preparing of the SnO2 NPs indicating electrons charge carriers. The electrical properties of the structure Al/SnO2 NPs/PS/c-Si/Al showed large increase in resistivity, more than the structure Al/SnO2 NPs/c-Si/Al because of the increase in depletion region width.

Abstract

In this project ZnO NPs / Si solar cells were fabricated by an efficient and size –controlled three-step method which consists of : (1) oxidation of metallic zinc (Zn) in hydrogen peroxide (H2O2) solution ,(2)spraying of the solution formed in step 1 onto substrates to form precursor films , and (3) oxidation of the precursor films in the air to form ZnO NPs films at different temperatures (100-500)0C . The structure of the nanoparticles films was investigated by X-ray diffraction (XRD) which indicates that ZnO NPs are in wurzite structure along (100) plane with particle size in the rang of(16.06-28.28)nm. The morphology of the nanoparticles films was studied by atomic force microscopy (AFM) which indicates that the average grain size of ZnO NPs is in range of (63.77-95.86)nm and the surface roughness increases as oxidation temperatures increase . The photoluminescence (PL) properties showed three peaks at ultraviolet , violet and green emission regions with shifting at ultraviolet emission region to longer wavelength . The band gap is found to be within the range of (3.85-3.96)eV . The ZnO NPs has n-type conductivity and the mobility was in the range of (5-22) cm2.V-1 .s-1. The electrical properties C-V and I-V of n-ZnO NPs /Si indicate that ZnO NPs /Si is abrupt heterojunction type . The saturation current decreases as oxidation temperatures increase . It was found that ZnO NPs/Si solar cells have maximum efficiency of 6.796% and VOC=0.379 V, JSC=25 mA/cm2 ,Jm =20 mA/cm2 ,Vm =0.340 V and FF=0.725 .The spectral response of ZnO NPs /Si solar cells showed three response regions and the maximum value was at 0.621mA/W at λ= 800 nm .

Abstract

Laser shock processing (LSP) was performed on brass and 2024-T3 Al alloys specimens to reveal its effect on microstructure and mechanical properties. LSP experimental array is as follows, A convergent lens is used to deliver 0.5-1J/pulse (1064 nm) and in a 10 ns laser pulse produced by Q-switched Nd:YAG laser with spots of a 0.5-2 mm in diameter moving forward along the workpiece at pulse density of 500 pulses/cm2. Water is used as the transparent confining layer and the non-prate black paint with a thickness of 20±2 µm is used as an absorbing layer. First, the effects of the LSP parameters as laser spot size, laser pulse energy and thickness of water layer on the surface micro-hardness and roughness were investigated. The experimental results show that, the surface roughness increases and the high micro-hardness would be generated near the surface due to LSP. The spot size decrease caused increase in surface roughness and micro-hardness due to increase in laser shock pressure. The surface roughness and micro-hardness increase with laser pulse energy increase. The optimum thickness of water layer was 3mm. Second, at the optimum values of 1mm spot size, 1J pulse energy and 3 mm water layer thickness, LSP effective parameters, microstructure and mechanical properties were evaluated. Microstructure and mechanical test include surface morphology by SEM, grain analysis by AFM, micro-hardness depth distribution, wear resistance, fatigue resistance and corrosion resistance. Results show that LSP impact has some thermal effects at the metal surface, it can refine grains and induce compressive residual stresses at depth of 0.8 mm. LSP impact can improve the wear resistance of brass and 2024-T3 Al, where the wear rate is reduced by 79% for brass and 67% for 2024-T3 Al compared with the untreated LSP specimens due to work hardening and compressive residual stress of LSP impact.. The results demonstrate that the LSP can improve fatigue resistance for brass and 2024-T3 Al alloys. By comparing with the untreated specimens, the fatigue lives of the specimens after LSP were obviously increased by 64% for brass and 73% for 2024-T3 Al at lower stress level due to the compressive residual stresses near the surface. Effects of LSP on electrochemical corrosion resistance of brass and 2024-T3 Al in 3.5 wt.% NaCl were investigated. Results show that the corrosion resistance with LSP impact is improved. The polarization resistance of brass and 2024-T3 Al is increased by more than five times compared with untreated LSP samples.

Abstract

Consolidation casting method has been successfully used to produce porous ceramics at low producing cost. In this work, porous calcium phosphate (CaP) ceramics have been produced by using natural additives (ovalbumin and albumin) proteins and (corn and rice) starches with (0, 5, 10, and 20) wt%. The mixture of proteins and calcium phosphate powder were dried at 60oC for 12 hours, while the mixture of starches and calcium phosphate powder were dried at 80oC for 2 hours. These samples were sintered at different temperatures (1100, 1200, 1300, and 1400oC). Many mechanical and physical tests were used to determine the properties of the prepared ceramic material which involved the linear shrinkage, water absorption, apparent porosity, compressive strength, scanning electron microscope SEM, and X-ray diffraction. The results showed that the types of additive affect the physical and mechanical properties of the ceramic produced. The water absorption and apparent porosity have been found to decrease with increasing sintering temperature, but the linear shrinkage and compressive strength has been found to increase with increasing sintering temperature of calcium phosphate mixture. Moreover, the increasing in compressive strength revealed an increasing in the evaluated properties. The linear shrinkage, apparent porosity, and water absorption showed an increase with increasing binder's content of calcium phosphate mixture for all binders, except for the ovalbumin has been decreased with increasing binder's content.

Abstract

Practically all material changing into nano as long as their grain radius become smaller than Bohr radius. InAs semiconductor having the second large Bohr radius and having also a small band gap which makes us choosing as a material for our study. To deposited nanoInAs spray pyrolysis was adopted since it is cheap and gives the possibility of controlling thin films characteristics. In this work a three principle parameters was studied, the first is spraying time, the second was the substrate temperature and the third was the solution morality in order to determine the best deposition conditions which could be used in making hetrojunction Measurement emerged that the crystal structure of thin films change significantly with change spray parameter on the optical and electric properties ,where describes the X-Ray schemes that all films were multiple crystal and levels of crystalline most frequent and highest intensity levels were(111) and (200) at the diffraction (25.442)°and (29.442)° respectively In addition to this was the expense of some structural characteristics such as grain size, strain, micro strain and the lattice constant. Thickness increased linearly with increasing temperature, while decreasing thickness at temperature higher than 300 C°,as well as thickness increased linear with increasing spray time. Analysis of transmittance and absorbance spectrum, using UV-VIS spectroscope at range(200-1100)nm was to increase thin films impact on those properties where there is no permeability spectral the region of at least 300nm, and then show a sharp increase in permeability and stabilizes after 400nm at temperature 250C° and 270C° and at higher temperature less permeability. Repeated the same results at different times of spraying. As the spectral absorbance it show quantitavely exclusively of energy gap at 300nm wavelength. And repeated the same energies at different spray time. Energy gap was greater than the value in mass situation and decreases with the spray time and temperature of substrate An addition, the increase in temperature deposition led to increased electrical conductivity, as to the results of the adoption of connectivity on the spray time also found that the conductivity increases with spray time.

Abstract

In this work TiO2 thin films were prepared by using spray pyrolysis technique ,which is a simple and inexpensive technique suitable for large deposition area. Many parameters have been considered in this study to specify the optimum condition ,namely (annealing temperatures , annealing time and doping). Structural,optical and electrical properties of TiO2 thin films were investigated and analyzed extensively with different conditions. Structure and surface morphology of TiO2 thin films were characterized by X-ray diffraction ,Atomic Force Microscope and Scanning Electron Microscopy measurements. Annealing in air at different temperatures of (450,500,550 and 600) ̊ C at constant time (90 min),also for different time of (60,90 and 120) min at constant temperature (550̊ C) was achieved. X-ray analysis has confirmed the formation of anatase phase with slight increases in crystaline size ,with increasing annealing temperature and annealing time . Effect of doping with chromium on structure and surface morphology, optical and electrical properties was studied.The X-ray diffraction indicates that all the grown films show the anatase phase with decrease in crystaline size with increasing of doping concentration. As a result, it has been found that films structure and properties strongly depend on doping concentration . The optical properties of TiO2 thin films were studied such as transmittance, extinction coefficient, absorption coefficient and energy gap for different parameters (annealing temperatures , annealing time anddoping).The transmittance was measured in the wavelength range from(300nm to 1100 nm) for all the films. The optical energy band gap was increased with the annealing temperature and time in range of (3.1 to 3.5) eV,while decreas in optical energy gap with increase in doping concentration in range of (3.5 to 3.2) ev. The resistivity decreases with increasing annealing temperature , annealing time and doping concentration. Hall measurements indicate that the TiO2 thin films of n- type semiconductors for different parameters. The sensitivity toword NH3 gas has been measured ,whereTiO2 doped with (Cr) has a sensitivity higher than pure.

Abstract

In this work nano PbS films were prepared using chemical bath deposition technique, which is a simple, inexpensive and suitable technique for large deposition area. Lead acetate salt was used as a source of lead ions and thiourea as a source of sulfide ions. During deposition several growth parameters have been considered in this work to specify the optimum conditions, namely (deposition time, temperature of path solution, pH value, lead ion concentration and thiourea ion concentration).The structure, optical and electrical properties of nano PbS films were investigated and analyzed extensively for a variety of growth conditions. The structural characteristic of the films prepared on a glass substrates have studied using X-ray diffraction, results shows that all the films were polycrystalline cubic structure for all deposited films under different growth conditions. The electrical properties of these films were studied. The d.c conductivity for the deposited films increases from 4.1*10-6 to1.5*10-5(.cm)-1 with thickness increases. From study of the electrical conductivity with temperature the films shows two activation energies Ea1 and Ea2 which are decrease from 0.567 to 0.351 eV and from 0.302 to 0.119 eV with thickness increases. Hall measurements showed that all the films are p-type and carrier concentration increase from (4.4 3 * 1015 to 2.5* 1016) cm-3 with thickness increase. Also we observed that the mobility were decreases with increasing of thickness. Optical measurements (transmission and absorption) were carried out. Transmittance decreased with increasing the deposition time, temperature of solution and pH value, while the transmittance increased with increasing lead ion concentration.The direct optical energy band gap range was between (1.68 -2.4) eV. Nano crystalline PbS was deposited on the n- type silicon to study and characterize the heterojunction. The I-V characteristics of the PbS/n-Si heterojunction have been studied,where the current-voltage characterization under dark conditions shows that forward bias current variation exponentially with voltage bias. Under illumination, the photocurrent density decreases with increase of deposition time. The reverse bias capacitance for PbS/n –Si heterojunciton was measured as a function of bias voltage at the frequency 200 KHz, and it is indicated that these heterojunction are abrupted. The capacitance decreases with increasing the reverse bias voltage. High spectral responsivity of 0.44 A/W, quantum efficiency 80% , and specific detectivity 1.98 * 1011 cm Hz1/2 W-1 where obtained. Also the shape of the spectrum of nano PbS/n -Si is extended into the blue region, due to widening of the window band gap.

Abstract

In this work the preparation of NiFeAlO4 nano ferrites samples, were synthesized by using sol-gel auto combustion method at temperature about 200°C. Then pelletized and sintered at different temperatures (900, 1000, 1100 and 1200°C). The formation of inverse spinel structure and inherent properties of high electrical resistivity, dielectric losses and high density material. The present work focused on studying the structural and electrical properties of NiFe2-xAlxO4 , where (x=0, 0.2 ,0.4, 0.6, 0.8, 1, 1.2, 1.4) using many analysis’s like x-ray diffraction ,LCR meter, FTIR and AFM. The results show that the chemical composition has a major effect on electrical, structural, and physical properties. Crystalline ferrite nano- powders and grains were synthesized with (19-22.6 nm) nano-sized particles, and (34-52 nm) nano-sized sintered grains. The phase analysis done by x-ray diffraction method confirmed the formation of the expected ferrites structure, where lattice parameter and crystallite size were increased but the x-ray density was decreased when increasing the Al content in NiAl ferrites. Resistivity of all samples have been measured at temperatures in the range of (300-540)K and found to decrease with the increasing of temperature this behavior is the same as in semiconductor, and resistivity and temperature diagram was used to calculate the activation energy. The FTIR spectra of NiFeAlO4 were charted in the range of 500 cm-1 to 4000 cm-1 FTIR Spectrum of different compositions in the series. However a shift in the peak positions and intensity was observed. Either in the examination of AFM noted that the grain size and roughness were increased with oxidation temperature. The dielectric properties were measured using (LCR) meter in the frequency range of (100 KHz – 6 MHz). Dielectric constant (εr'), the loss tangent (tanδ) and the loss factor (εr′′) were calculated from capacitance data. The dielectric parameters decreased with the increase of the frequency. This behavior is typical of ferrite materials as explained by Koop’s model. The result also showed that the Conductivity and dielectric loss increased with the increase of the Al content for NiAl ferrite, while conductivity and dielectric constant decreased with the increase of the amount of Fe ion for NiAlFe -ferrite. The resistivity of samples were found to increase the amount of Fe batter than the models of sintered samples.

Abstract

In this work, a series of Cd1-xZnxS 0.05 ≤ x ≤ 0.7 ternary thin films were prepared on glass substrates using chemical bath deposition (CBD ) method. An attempt was made to modify the band gap of CdS (2.4 eV) by preparing a mixed lattice with a high band gap material, ZnS (3.7 eV), giving a new set of materials. Cadmium sulphate, Zinc sulphate, and thiourea are used as the basic source materials in the deposition bath. Many growth parameters have been considered in this study to specify the optimum condition, namely (temperature of solution, pH, and deposition time) for properties Cd0.5Zn0.5S thin film. Structural, optical and electrical properties of Cd1-xZnxS thin films are investigated and analyzed extensively with respect to growth conditions. The Cd1-xZnxS films are annealed in air at temperatures (300) ºC at constant time of ( 60 min). Structure and surface morphology of Cd1-xZnxS thin films were characterized by X-ray diffraction (XRD), Atomic Force microscope (AFM), Optical Microscopic, and Scanning Electron Microscopy (SEM) Measurements. The XRD indicates that all the grown films show only one diffraction peak located at (2θ= 26.7°) with hexagonal structure in predominant (002). The average grain size changes from (9.3nm to 4.48nm) with the increase in Zn- content (x = 0 to 0.65). It was found that as the Zn- content increases, the peak intensity decreases and for (x ≥ 0.7) the films have amorphous character. The values of lattice constant ‘a’ and ‘ c’ have been observed to vary with composition from (5.75 nm to 4.68 nm) and (6.66 nm to 6.62 nm), respectively, with the increase in Zn- content ( x = 0 - 0.65) . The AFM studies showed that the smooth surface texture was observed in the deposited Cd1-xZnxS films with (x= 0.3) , the surface roughness of the Cd1-xZnxS thin films is about ( 2.66nm to 9.47nm) and the root mean square (RMS) is about ( 3.41nm to 11.9nm) with increase in Zn- content (x = 0.3 to 0.6) .The optical microscopic measurement observes that films surface become increasingly coarse at increasing the Zn- concentration. The SEM exhibits that grains in the film are distributed to cover the surface of the substrate completely, the grains become small in diameters with increasing Zn-contents. The optical properties of Cd1-xZnxS thin films were studied by the transmittance, absorption coefficient and energy gap for deposition conditions (80ºC temperature pH= 10 and time 3h). The transmittance is measured in the range from ( 300 nm to 900 nm) for all the films, in the visible wavelength region, the average transmittance greater than (80 %) at Zn-content (x = 0 to 0.7). The Cd1-xZnxS thin films have high optical absorption coefficients where the value reaches at (1.2×105 cm-1). The energy band gap ( Eg) values of Cd1-xZnxS thin films are ( 2.4 eV to 3.4 eV) corresponding to the Zn-content ( x = 0 to 0.7) respectively. In other word, the optical band gap of Cd1-xZnxS thin films become wider as Zn-content increases. All the Cd1-xZnxS films show that the resistivity varied in the range ( 0.45× 103 Ω.cm to 5.9× 103 Ω.cm) corresponding to the Zn-content (x = 0 to 0.7), respectively. Also the activation energies Ea1 (0.124 eV to 0.833 eV) and Ea2 (0.063 eV to 0.277 eV) varied with the increasing Zn-content (x) in the films (x = 0 to 0.7). Hall measurements indicate that the Cd1-xZnxS thin films have same conduction type (n-type) conductivity. The carrier concentration and mobility values for Cd1-xZnxS thin films vary with zinc content , furthermore their values are (5.201× 10¹² cm-3- 1.263× 1012cm-3) and (140.5 5 cm2V-1S-1 - 22.435 cm2V-1S-1 ) respectively.

Abstract

In this project, porous silicon preparing by electrochemical etching (ECE) technique using different parameters such as silicon orientation ((100) & (111)), etching time (5, 10, 20 & 35 min), current density (10, 20, 30 & 40 mA/cm2) and HF concentration (15%, 20% & 30%). And next step of project was deposition of ZnO thin film on glass by spray pyrolysis technique from Zinc nitrite and study the effect of changing thickness of ZnO film (100, 200, 500 & 800 nm). And the final step of project consist deposition ZnO film on PS. The measurement refer with nano- structure (mesoporous silicon), the PS (100) gives the characteristics of nanoscale better than directional silicon (111) due to the crystal structure and the different in interaction between the HF electroyied and silicon. And The measurements of ZnO refer n-type semiconductor with hexagonal structure (polycrystalline structure) and this structure helps to emit several wavelengths from ZnO, also the decreasing of ZnO thickness leads to increasing in energy gap due to decreasing in grain size . And when when ZnO was deposited on PS the properties of both ZnO and PS will improved, where the structure properties showed the deceasing in crystal size with good adhesion between ZnO and PS. Morphology showing crystalline regularity and growth of ZnO film and improving of structural stability of the PS substrate. Optical measurement (PL & R%) shows increasing in absorption of light with increasing in blue shift of PS and increasing in UV emission of ZnO film, Raman measurement show quantum confinement in PS layers with decreasing in variation mode of ZnO film, and the electrical properties of ZnO/PS show large increasing in resistivity come from increasing in depletion layer of the sponge structure of Al/ZnO/PS/c-Si/Al .

Abstract

The present work concerned the study of pulsed plasma generation by a 6 ns Nd: YAG pulsed laser at 1064 nm wavelength with a maximum pulse energy of 500 mJ focused rough on Al and Fe solid target samples in air at atmospheric pressure and vacuum. The emitted spectrum from the plasma plume was in the range of [300–750] nm and was recorded using a monochromator and Silicon Photo Detector (PD). Measurements of electron temperature and electron density of the produced plasma at different laser energies and at different vacuum pressures are described using different emission spectral lines. Plasma diagnostics are based on optical emission spectroscopy and Local Thermodynamic Equilibrium (LTE) assumption. Excitation temperature of plasma is determined from the Boltzmann plot. Temperature of Al plasma at atmospheric pressure was 1eV (11600 Kº) and at vacuum pressure was 1.22 eV (14144.9 Kº). Temperature of Fe plasma at atmospheric pressure was 1.466 eV (16997.1 Kº) and at vacuum pressure was 1.711 eV (19837.6 Kº). The electron density was determined from the FWHM of the Stark broadening. The electron density for Al plasma at atmospheric pressure was 7.0×1018 cm−3 and at vacuum pressure was 7.5×1018 cm−3. The results of the electron density for Fe plasma at atmospheric pressure was 8.2×1018 cm−3 and at vacuum pressure was 9.0×1018 cm−3. Also the results show a maximum value of electron density at delay time of 5.5µs after laser pulse. Also the results show intensity thresholds for Al plasma, and the saturation at laser energy of 420 mJ. Also the results show intensity thresholds for Fe plasma and the saturation at laser energy 500 mJ.

Abstract

Practically all material changing into nano as long as their grain radius become smaller than Bohr radius. InAs semiconductor having the second large Bohr radius and having also a small band gap which makes us choosing as a material for our study. To deposited nanoInAs spray pyrolysis was adopted since it is cheap and gives the possibility of controlling thin films characteristics. In this work a three principle parameters was studied, the first is spraying time, the second was the substrate temperature and the third was the solution morality in order to determine the best deposition conditions which could be used in making hetrojunction Measurement emerged that the crystal structure of thin films change significantly with change spray parameter on the optical and electric properties ,where describes the X-Ray schemes that all films were multiple crystal and levels of crystalline most frequent and highest intensity levels were(111) and (200) at the diffraction (25.442)°and (29.442)° respectively In addition to this was the expense of some structural characteristics such as grain size, strain, micro strain and the lattice constant. Thickness increased linearly with increasing temperature, while decreasing thickness at temperature higher than 300 C°,as well as thickness increased linear with increasing spray time. Analysis of transmittance and absorbance spectrum, using UV-VIS spectroscope at range(200-1100)nm was to increase thin films impact on those properties where there is no permeability spectral the region of at least 300nm, and then show a sharp increase in permeability and stabilizes after 400nm at temperature 250C° and 270C° and at higher temperature less permeability. Repeated the same results at different times of spraying. As the spectral absorbance it show quantitavely exclusively of energy gap at 300nm wavelength. And repeated the same energies at different spray time. Energy gap was greater than the value in mass situation and decreases with the spray time and temperature of substrate An addition, the increase in temperature deposition led to increased electrical conductivity, as to the results of the adoption of connectivity on the spray time also found that the conductivity increases with spray time.

Abstract

In this work preparation NiZn and NiZnMg nano ferrites samples , using sol-gel auto combustion method at temperature about 2000C, then pelletized and sintered at different temperatures (1273, 1373 and 14730k).They have showed spinel structure and inherent ‎properties of high electrical resistivity, low electrical losses and high ‎density material. Therefore, these ferrites have a potential candidate for high frequency applications The present work is study the electrical and structural ‎properties of Ni1-xZnxFe2O4 and Ni0.7-yZn0.3MgyFe2O4, where (x=0, 0.1, ‎‎0.2, 0.3) and (y=0, 0.1, 0.2, 0.3) respectively, and shows effect of chemical composition ‎on electrical, structural, and physical properties. Crystalline ferrite nano- powders and grains were successfully synthesized and the ‎process has resulted in the formation of (19-22.6 nm) nano-sized particles, and (34-52 nm) nano-sized sintered grains. Chemical phase analysis carried out by x-ray diffraction method ‎confirms the formation of the expected ferrites structure, where lattice parameter and crystallite size increase but the x-ray density and porosity ‎decreased when increasing the Zn content in NiZn ferrites. Also the same behavior takes place when Mg content increases in NiZnMg-ferrites. Resistivity of all samples have been measured at temperatures in The range of ‎‎ (300-540) K0 and found it decreases with the increasing of temperature like ‎a semiconductor, and resistivity and temperature were used to calculate the ‎activation energy. Activation energy results showed decreases when increase the Zn content in NiZn ferrites. Resistivity and activation energy both are increasing with high concentration of Mg ions. The dielectric properties are measured using (LCR) meter in the frequency ‎range of (100 Hz – 200 kHz), dielectric constant (εr'), the loss tangent ‎‎ (tanδ) and the loss factor (εr′′) are calculated from capacitance ‎data, that the dielectric parameters decrease with increase of the ‎frequency.‎ model. This behavior is typical of ferrite materials as explained by Koop’s model. Conductivity and dielectric loss were increased ‎with the increase of the Zn content for NiZn ‎ferrite, while conductivity and dielectric constant were decreased with increase the ‎amount of Mg ion for NiZnMg -ferrite.‎ Found the resistivity of samples increase the ‎amount of Mg batter than the models of sintered samples.

Abstract

Porous silicon (PS) layers have been prepared in this work by electrochemical etching (ECE) technique of a (111) p-type silicon wafer with resistivity (1.5-4 Ω.cm) in hydrofluoric (HF) acid of 20% concentration. Various affecting parameters were studied such as the current density (10, 20, 40, and 50 mA/cm2), and etching time (10, 20, and 40 min). We have studied the optical properties (Reflectivity), vibration properties (Raman), surface properties (FTIR), structural properties (XRD), morphological properties (AFM), and electrical properties (I-V, C-V, photocurrent, and photosensitivity). Also we prepared PS layers by ECE for p-n silicon at different current densities (5, 10, and 40 mA/cm2) with fixed etching time at 20 min, in 20% HF acid, in order to study the photovoltaic measurements for solar cell. The PS surface showed lower reflectance values compared with bulk silicon. Raman spectra measurements showed a broadened peak and shifted below 520 cm-1 for PS layers. In freshly prepared PS layer, the FTIR studies demonstrated the presence of silicon-hydrogen bonds, related to groups formed at the extended PS surface. As the PS layers were stored, various silicon-oxygen vibrational modes became apparent. X-ray diffraction showed when crystal size was reduced toward nanometric scale, then a broadening of diffraction peaks (111) were observed and the width of the peak was directly correlated to the size of the nanocrystalline domains. AFM images showed the PS layer had sponge like structure, and average diameter of pore and thickness of PS layer increased with increasing the current density and etching time. The electrical properties of prepared PS; namely current densityvoltage characteristics in dark, showed that the pass current through the PS layer decreased by increasing the current density and etching time, due to increase the resistivity of PS layer. The PS layer showed a rectifying behaviour with different rectification ratio. C-V measurements demonstrated that the charge carries decrease and width of depletion layer increase by increasing the current density and etching time. The photosensitivity measurements of prepared PS layer showed the peak value in visible region at (400-600nm) increased with increasing the current density and etching time.

Abstract

This thesis presents new, easy, and quick methods to prepare silver nano-particles at high concentrations without aggregate, non-toxic and free of pollution. The size and properties of these particles are controlled. The AgNPs are prepared the approach chemical reductive silver salt solution (AgNO3) with seven different methods. The main difference between the methods adopting different reducing agents and methods that used same reducing agents but of different quantities is explained. The AgNPs are found to be pure and stable for long time. Structures confirmed from X-ray diffraction (XRD) and the crystillate size was determined using Scherrer's equation to be about 32 nm (for AgNPs were prepared by 1mM of AgNO3 reduce with 2 mM NaBH4). Effect of chemical solutions are studied utilizing absorption spectra measures. This is used to get knowledge of the better concentration for the preparation of NPs, which improves the efficiency of the generation of NPs in the manner of the chemical method. Solutions of NaBH4 at 2 mM, and (CTAB) at 0.8 mM, and oxalic acid at 14 mM, are found to enhance the efficiency for all the generation and the disperse, however, reduceing the aggregation of the AgNPs. Absorption spectra for AgNPs showed a sharp and single absorption peaks. In this search, the peak is extend between range 385-600 nm which indicates the generation of NPs of pure silver. Better concentration for the preparation of silver particles in different solutions such as for NaCl was 5 mM, and PVP at 6 mM, where this concentration enhances the efficiency for all generations, size, dispersion, and prevents aggregation of the NPs prepared. Nanocompsite matter was prepared from AgNPs, and a polymer PVA. Decrease band gab energy for polymer PVA is tuned by adding different concentrations of AgNPs (from 5.82 eV to 2.65 eV).

Abstract

In this work, a series of Cd1-xZnxS 0.05 ≤ x ≤ 0.7 ternary thin films were prepared on glass substrates using chemical bath deposition (CBD ) method. An attempt was made to modify the band gap of CdS (2.4 eV) by preparing a mixed lattice with a high band gap material, ZnS (3.7 eV), giving a new set of materials. Cadmium sulphate, Zinc sulphate, and thiourea are used as the basic source materials in the deposition bath. Many growth parameters have been considered in this study to specify the optimum condition, namely (temperature of solution, pH, and deposition time) for properties Cd0.5Zn0.5S thin film. Structural, optical and electrical properties of Cd1-xZnxS thin films are investigated and analyzed extensively with respect to growth conditions. The Cd1-xZnxS films are annealed in air at temperatures (300) ºC at constant time of ( 60 min). Structure and surface morphology of Cd1-xZnxS thin films were characterized by X-ray diffraction (XRD), Atomic Force microscope (AFM), Optical Microscopic, and Scanning Electron Microscopy (SEM) Measurements. The XRD indicates that all the grown films show only one diffraction peak located at (2θ= 26.7°) with hexagonal structure in predominant (002). The average grain size changes from (9.3nm to 4.48nm) with the increase in Zn- content (x = 0 to 0.65). It was found that as the Zn- content increases, the peak intensity decreases and for (x ≥ 0.7) the films have amorphous character. The values of lattice constant ‘a’ and ‘ c’ have been observed to vary with composition from (5.75 nm to 4.68 nm) and (6.66 nm to 6.62 nm), respectively, with the increase in Zn- content ( x = 0 - 0.65) . The AFM studies showed that the smooth surface texture was observed in the deposited Cd1-xZnxS films with (x= 0.3) , the surface roughness of the Cd1-xZnxS thin films is about ( 2.66nm to 9.47nm) and the root mean square (RMS) is about ( 3.41nm to 11.9nm) with increase in Zn- content (x = 0.3 to 0.6) .The optical microscopic measurement observes that films surface become increasingly coarse at increasing the Zn- concentration. The SEM exhibits that grains in the film are distributed to cover the surface of the substrate completely, the grains become small in diameters with increasing Zn-contents. The optical properties of Cd1-xZnxS thin films were studied by the transmittance, absorption coefficient and energy gap for deposition conditions (80ºC temperature pH= 10 and time 3h). The transmittance is measured in the range from ( 300 nm to 900 nm) for all the films, in the visible wavelength region, the average transmittance greater than (80 %) at Zn-content (x = 0 to 0.7). The Cd1-xZnxS thin films have high optical absorption coefficients where the value reaches at (1.2×105 cm-1). The energy band gap ( Eg) values of Cd1-xZnxS thin films are ( 2.4 eV to 3.4 eV) corresponding to the Zn-content ( x = 0 to 0.7) respectively. In other word, the optical band gap of Cd1-xZnxS thin films become wider as Zn-content increases. All the Cd1-xZnxS films show that the resistivity varied in the range ( 0.45× 103 Ω.cm to 5.9× 103 Ω.cm) corresponding to the Zn-content (x = 0 to 0.7), respectively. Also the activation energies Ea1 (0.124 eV to 0.833 eV) and Ea2 (0.063 eV to 0.277 eV) varied with the increasing Zn-content (x) in the films (x = 0 to 0.7). Hall measurements indicate that the Cd1-xZnxS thin films have same conduction type (n-type) conductivity. The carrier concentration and mobility values for Cd1-xZnxS thin films vary with zinc content , furthermore their values are (5.201× 10¹² cm-3- 1.263× 1012cm-3) and (140.5 5 cm2V-1S-1 - 22.435 cm2V-1S-1 ) respectively.

Abstract

In this work ZnO Nanoparticles were fabricated using Liquid Phase Pulse Laser Ablation technique and gives very simple, cheap and a single step method for the preparation of zinc oxide Nanoparticles with no need for any complex or expensive further steps. Also, It shows a long period of stability, less aggregation, non toxic and contamination colloidal Nanoparticles, In addition this work provides a controlled method to prepare Nanoparticles with a specific properties depended on the preparation conditions and laser parameters. In the present work, at which ablation of pure Zn metal target in DIW was accomplished using 9 nsec Q-switched Nd:YAG laser at (1.06 µm) laser wavelength , at different laser fluence and number of laser pulses, and the effect of these parameters on optical, photoluminescence, amount of ablated material, structural and surface morphology have been studied. The atomic absorption result shows that the amount of the ablated material is directly proportional to the laser fluence and number of laser pulses. The UV-Visible show a red shift in the absorption spectra related to the shift in the energy gap due to the size increase in the particle size with to higher laser fluence. A blue shift was however recognized with a larger number of laser pulses. The photoluminescence result gives a blue shift with the decrease in laser fluence and number of laser pulses. The X-Ray diffraction pattern revealed the presence of (100) plane related to ZnO wurtize structure. The Fourier transform infrared spectroscopy result shows that the intensity of the Zn-O bond vibrational mode is proportional directly to the laser fluence and the number of laser pulses. Grain size of the obtained NPs are found to increase with laser fluence and decreased with the number of laser pulses as shown by the AFM result.

Abstract

Abstract

In this work, we prepared a thin film of In2O3 by rapid thermal oxidation at different thickness (106-200-350-500nm) within a range of oxidation temperature (350-400-450C°). Two types of substrate have been used in this work; the structural, optical and electrical properties have been studies for those films which prepared on glass substrates. Also the films are deposited onto the second type p-n junction's silicon solar cells, to study the performance of this film as antireflection coating. The structural properties for the prepared films In2O3 were studied through tests optical microscope and X-Ray diffraction, it is appeared that the film, is polycrystalline. The optical properties show an increasing in transmission characteristics at the visible (400-700nm).the direct energy band gap have been increased with increasing the film thickness from (3.41-3.63eV),however for indirect it is increased with thickness from (2.25-2.65eV). The calculations also included some optical constants such that transmittance, absorption coefficient and refractive index. The electrical properties of In2O3 film, shows that the activation energy of the film to be about (0.5-0.38eV) in the range of temperature (30-150 C°) and results of Hall effect shows that the type of the film is (n-type) ,and that the Hall constant decreases as thickness increases. The measurement of the short circuit current-open circuit voltage show improved with conversion efficiency of the p-n junction solar cell after coating by In2O3 film an increases film thickness and oxidation temperature ( 3.95%) before coating it became (10.95%) after coating by In2O3 film 500nm thickness at 450C° oxidation temperature And through the study of the detectives properties ,the maximum spectral response at the wave length 800nm was (0.126A/W) before the coating improved after coating it became (0.45A/W) ,at the same wavelength, as for the Quantum efficiency ,it was( 1.95%) before the coating became ( 7%) at the same wave length by In2O3 film 500nm thickness at 450C° oxidation temperature . And at studying of the short circuit current-open circuit voltage of the solar cell before and after texturing and coating by In2O3 film show improved with conversion efficiency (0.29%) before texturing , while after texturing and coating by In2O3 film it became (3%) also show the measurement improved with spectral response and Quantum efficiency , was the maximum spectral (0.036A/W) before texturing at the wave length 800nm improved after texturing and coating by In2O3 film it became (0.24A/W) ,at the same wave length, as for the Quantum efficiency ,it was(0.55%) before the texturing it became ( 3.83%) after the texturing and coating this to make the film as anti reflecting coating .

Abstract

In this work ,the study of structural,optical and electrical properties of (CdTe) thin films which was prepared by thermal vacuum evaporation on glass substrate at room temperature, the annealing effect and CdCl2 heat treatment effect at (300˚C) temperature for (15min) time on the film properties was studied, in addition to study the effect of CdCl2 heat treatment for various molariries (0.1,0.2,0.3)M ,dipping time (5,10,15)min and anealing time (5,15,30)min on the properties of films . The structural studies have been performed by X-Ray diffraction technique which showed that the deposition film is polycrystalline in nature , and increasing in the grain size after annealing and CdCl2 treatment and contrast in appearence and disappearence of planes in crystal structure, optical microscope was employed to study the surface morphologies . From optical measurement , the deposited film have direct energy band gap (Eg) and it was found to be (1.56,1.54,1.48) eV for deposited films at room temperature and annealed without and with CdCl2 treatment at (300˚C) for (15min) respectively . The electrical measurements explained that D.C. conductivity increased after the film annealing and CdCl2 treatment and all films have two values of activation energy (Ea1) and (Ea2) and found that it decreased after annealing and CdCl2 treatment , from the study of Hall effect , all samples showed that (p-type) with carriers concentration (p) and mobility () increases after annealing and CdCl2 treatment , from the results of current – voltage characteristics for dark and illumination of CdTe thin films explain that the dark and photo current increased after annealing and CdCl2 heat treatment .

Abstract

Transparent Conducting Oxide (TCO) is a Special Type of Material, Since They have Metallic Electrical Conductivity and at same Time They are Highly Transparent and for a Wide Range of Wave length. The Band Gab They Have Makes Them suitably for a wide Rang of Application's Cadmium Oxide (CdO) is one of These Oxide, Which have been Used Studied Vastly and a different method have been used for the Deposition. in this Work we Oxidize Cadmium Thin Film's Which already Deposited by D.C Sputtering. During The Work, we Studied the Heat of annealing Temperature and annealing Time from the Work all Treated Film's was Polycrystalline with different Diagram according to annealing parameter. The plane (111) is the predominate and with the (200)&(220) the Cadmium plain appeared only for the Film annealing with (2)mint and (200º C) , also it is appeared with annealing Temperature (100º C) and (30)mint from the Optical measurement we a sure that the Band Gab is direct With value Ranged between (2.4-2.7)eV and the Transition are allowed direct certain Sample. Which Show littlie bit and this may be due to defect al Film's have high absorption Coefficient Ranged (104-105)cm-1 also Electrical measurement shoed They Activation Energy Ranged (0.013-0.12)eV which means that Fermi level is near by films have highly Electrical Conductivity (102 – 103) Ω-1.cm-1 which is Probability due to the Presence of Cadmium atoms.

Abstract

Use Iraqi Bauxite (64.2%) Alumina was calculated at (1400 ) and Grain gradient limited after add kaolin and Sodium Silicate to increase compaction bauxite grain and then addition different weight percentage from zirconia to mixture (20%, 15%, 10%, 5%). The samples were formed by using bi- axial pressing. These samples were fired in two temperatures (1200 , 1400 ) . Studies the physical properties (Shrinkage, density and porosity), thermal properties (thermal conductivity, thermal expansion , specific heat capacity, and thermal shock), mechanical properties (compression strength , and Diametrical strength). Found from measuring get simple change in (Shrinkage dimension and thermal expansion) with add ZrO2 , increasing of zirconia percentage leads to decreasing of (mass shrinkage , porosity, thermal conductivity, specific heat capacity). And increasing of (density and compression strength). Add zirconia effected on properties from two side; first from side properties and another from side made zirconium silicate phase.

Abstract

The research involves the use of lightweight aggregate (perlite) with Portland cement to make perlite mortar using to Improve the thermal isolation and fire proof for masonry units. The cement:perlite ratio was [ 1:7, 1:5.6, 1:4.7, 1.4, 1:3.5] by volume. The research involves a study of mechanical, thermal and physical properties for all specimens that had been make in normal situation. One of the mechanical properties, which were study, is the percentage of flow to know the amount of flow ability and maintained between (90 – 100 %). Where the mechanical and physical tests are the 28 days air-dry density and compressive strength respectively. In addition, for the thermal properties that have been study are the thermal conductivity and time endurance on the flame for dry specimens in 60 day old. The other physical properties are the study of the effect of increasing the thickness or the amount of cement of specimens at the time endurance on fire. Generally the result shows that the increasing of cement quantity are improves the workability of the mortar and decreasing the water-cement ratio as comported to a mortar poor in cement moreover that rising up the value of compressive strength and air-dry density. In another hand the experimental work proof that the increasing of cement ratio on the mix (mortar) is effect negatively on the thermal properties of the dry mortar by increasing the value of the thermal conductivity and decreasing the time endurance on the fire for the tested specimens moreover that increase the cracks and make it show early. Moreover above, when we fix the cement:perlite ratio in the mortar and increasing the thickness of the specimens to study the physical properties We found that the increasing effect positively on the time endurance on the fire. In addition, from all physical and thermal experimental that has been making we found that the perlite is working like a scattering material for the heat, because of its porosity, that can contain the air inside it and this porosity make the heat transfer be slower as comported with another solid material, and for all of this, the perlite is one of most successful isolations for a heat less than 800 degrees.

Abstract

BaxSr1-xTiO3 (BST) ferroelectric nano powders were processed with three concentrations (x = 0.5, 0.7 and 0.9) by reacting TiO2 powder in aqueous solution of BaCl2 and SrCl2 using a technique known as oxalic acid route. A sintering process has been done at temperature (800oC, 1000 oC and 1100 oC) and a soaked time (1.5h, 2.5h, 4h), in this step, the solid phase reaction takes place between the constituents giving the ferroelectric phase. XRD analysis has been carried out in order to examine the appearance and the stability of the BST ferroelectric phase. Also the grain size obtained from this test which reached to (15.4, 34.65, 42.13 nm) for the three concentrations (x = 0.5, 0.7 and 0.9) respectively. The ferroelectric phase was subjected to several tests to obtain some of the BST ferroelectric properties. The microstructure test which gives a clearly observation about the distortion and the grain growth for the same subjected samples to the XRD analysis. Then, an electrical test involves a permittivity with temperature, the permittivity reached to (more than 530,700 and 500) at Curie temperature, while the loss factor reached (0.175, 0.19, and 0.2). The quality factor and the resistivity with temperature were examined too, all these tests have been done for the three concentrations of BST system. Moreover permittivity, loss factor and the quality factor with frequency in ranges (103 - 105 Hz) were studied and we found that these tests (permittivity, loss factor and quality) exhibit good stability in this range of frequency. The last test was the breakdown strength test. The BST apparent densities were (5.5, 5.5, 5.45) gm/cm3 for (x = 0.5, 0.7 and 0.9) respectively by using Archimedes law, while the bulk density and apparent porosity were calculated arithmetical. The shrinkage was too small for all of the three systems. In this investigation we found that the oxalic acid method is a good method to prepare a ferroelectric phase with high density and small porosity. The nano BST grains and the high density have large dependence in the electrical properties, which is clearly observed in the broaden of the permittivity and loss factor peaks, in other words the broaden indicated that the transition never depend on Curie temperature and this is an important property in microwave applications. The stability of the permittivity, loss factor and quality with frequency range (103 -105 Hz) imply to the good capability of using nano BST ferroelectric in tunable devices.

Abstract

تم تحضير متراكب بوليمري من بولي فانيل الكحول / بولي أنلين بعملية الاكسدة الكميائية للأنلين مستعملاً نوعين من العوامل المؤكسدة (6H2O. Fecl3) و (2H2O . Cucl2) وذلك بثلاث طرق تحضيرية:

1. تحضير نماذج من بولي فاينل الكحول بسمك (1 mm) ثم غمرها في مونو مير الانلين لمدة (3) أيام وبعد تجفيفها تم ادخالها في محاليل العوامل المؤكسدةالمحضرة بتراكيز مختلفة، وبأستخدام نوعين من المذيبات (الايثانول والاسيتونيترال)مستخدما فترات زمنية مختلفة لعملية البلمرة.
2. تحضير نماذج منبولي فاينل الكحول المحمل بالعامل المؤكسد (mm1) بتراكيز مختلفة وتم تعريضها الى بخار الانلين لمدة (12) يوم.
3. تحضير نماذج من بولي فاينل الكحول المحمل بالعامل المؤكسد(mm1) بتراكيز مختلفة وتم تعريضها الى بخار كل من الانلين وحامض الهيدروكلوريك بتركيز (1N) في انٍ واحد ولفترة زمنية محددة (7) أيام.

تم دراسة الخواص الكهربائية لنماذج المحضرة والتي تضمنت سلوك التيار الفولتية، التوصيلية الكهربائية وتأثير درجة الحرارة عليها. أظهرت النتائج ان النماذج المحضرة تمتلك خاصية توصيلية كهربائية والتي تعتمد على كل من تراكيز المحاليل المؤكسدة وزمن البلمرة وطريقة التحضير. تم التعرف على نوعية وتركيز وحركية حاملات الشحنة بتطبيق تأثير هول بينما طاقة التنشيط ونوع حاملات الشحنة بتطبيق تأثير سيبك والتي اظهرت ان حاملات الشحنة هي من نوع (P) واظهرت صفة أشباه الموصلات. تم التصوير المجهري وفحص X-ray لنماذج محددة.

Abstract

Structural, optical and electrical properties of copper sulfide films were investigated and analyzed extensively with respect to growth conditions. Annealing in vacuum at pressure 2x10-2 torr, different temperature (100,150,200,250 and 300) °C at constant time of 30 min, were adopted. The annealing process in different times (15,60,90,120, and 240) min at constant temperature of 200 ºC were adopted as well. The effects of doping on the properties of the films were studied. Two types of doping salts were used (AlCl3 & FeCl3) with four different weights (1, 1.5, 2 and 2.5) mg. From XRD, it has been fond that all films at different deposition parameters are amorphous, but annealed films showed some degree of crystallinity. Doping has no effect on the XRD. Optical measurements contained study of transmission and absorption by using spectrophotometer were carried out. Transmittance decreased with increasing the dipping number and doping weights, while the transmittance increased with increasing the time and temperature of annealing .The direct optical energy band gap range was between (2.17-2.56) eV. The electrical conductivity increased with increasing of dipping number, also with increasing the doping weight of Al .While the electrical conductivity deceased with the increasing of doping weight of Fe and with annealing time and temperature. The electrical conductivity was found to be (0.044- 45.453) (Ωcm)-1, whereas the activation energy was (0.115 -0.948) eV.

Abstract

the present work the compound of piezoelectric nanopowders with a general system PbZrxTi1-xO3 (PZT) at (x =0.3, 0.5 and 0.7) was prepared using organic acid precursor method. The prepared sample was subjected to some tests in order to obtain several of PZT piezoelectric properties. X-Ray diffraction (XRD) analysis was used to examine the growth and stability of PZT piezoelectric phases. Then grain sizes were measured (39, 36 and 30 nm) for (x=0.3, 0.5 and 0.7) receptively. The microstructure of the prepared sample was studied by using optical microscope to observation the distribution and the grain growth. Physical properties such as bulk density, apparent density, apparent porosity and the shrinkage were measured, where the value of bulk density reached (5.78, 6.11, 5.9 gm/cm3) at 1100oC for 2h. On the other hand, the shrinkage value was (0.064, 0.034, and 0.042) at 700Co when compared with the values (0.0055, 0.011 and 0.0092) at 1100Co at different concentrations (x= 0.3, 0.5 and 0.7) respectively. Electrical properties such as dielectric constant (εr) and dielectric loss (tanδ) were measured as a function of temperature. The value of dielectric constant were reached to (1000, 1200 and 1050) at curie temperature, while the dielectric loss reached (1.1, 1.05 and 1.15) at different concentrations (x= 0.3, 0.5 and 0.7) respectively. In addition electrical resistivity (Ro) and quality factor (Q) were measured as a function of temperature. Also the dielectric strength was measured. Also (dielectric constant, dielectric loss and quality factor) were measured as a function of frequency at range (103-105 Hz), were (εr=270, 365 and 235), (tanδ=0.375, 0.275 and 0.42), (Q=2.7, 3.7 and 2.5) at different concentrations (x= 0.3, 0.5 and 0.7) respectively.

Abstract

In this project an optical communication system was designed and implemented to transmit one-video channel simplex technique with line of sight . The constructed simplex optical communication system consists of a transmitter ( uses a laser beam of a wavelength λ = 650 nm as a carrier wave in free space ), and a receiver ( uses PIN diode as a detector ) each in one side. Intensity modulation (IM) technique has been used to transmit video signal of a frequency range (0~5) MHz bandwidth The video signal fed by monitoring camera type (X3 ) 231 and the voice signal fed by Mic, each signal will be amplified and converted to a modulated intensity of laser beam, sent to the associated receiver . Each receiver converts the laser signal to a weak electrical signal ; the signal will be amplified and converted back to an analoque signal to produce the original transmitted signal, and sent to TV set to be monitored in black and white color video with sound . The transmission range for the present system was five meters , that can be developed to suit for longer range .

Abstract

In this work study, deposition method adopted using solution to deposit lead iodide layers, the method is easy, low cost, provides the possibility of large area deposition at required thickness and dose not need sophisticated techniques. This research studies the influence of deposition under different conditions and doping in the properties of lead iodide layers. Four different deposition conditions are used (deposited samples in dark, deposited samples in dark under the influence of a magnetic field, deposited samples in light, deposited samples in light under the influence of a magnetic field). Also two types of salts dopants were used with four different weights (0.002, 0.0025, 0.003, 0.0035 g) namely: (AlCl3 and CoCl2). Current study focused on structural, optical and electrical properties of layer prepared under different conditions and doping. The experimental results of XRD showed polycrystalline hexagonal structure with four main peaks which correspond to: [(001) (002) (003) (004)]. It is found that both deposition conditions and doping don’t affect on lead iodide structural. The optical measurements data were analyzed and interpreted in term of direct electronic transitions. Transmission spectrum of undoped and doped lead iodide layers exhibit a sharp increment start around (~520 nm) and it becomes sharper with doping. It was observed that lead iodide has wide direct band gap (2.3 eV), the energy gap is affected by depositions conditions and doping; it decreases as samples deposited in dark and with increased doping weight. The electrical measurements showed that the electrical conductivity of PbI2 varies according to deposition conditions and doping. Pure samples showed highest value for sample which's deposited in dark with applied magnetic field (5.05x10-9Ω-1cm-1) and it increased when the film is illuminated by light to (5.15x10-8 Ω-1cm-1). The doped samples showed increasing in the value of dark current with increasing doping weight. The best ratio of photoconductivity to dark conductivity ( ) obtained from doping sample by (Co) doping in weight (0.002g). Also the activation energies determined for different samples and their values changed by the range of (0.38 - 0.162 eV).

Abstract

In this work CdO films were prepared by using chemical bath deposition technique, which is a simple, inexpensive and suitable technique for large deposition area. The cadmium nitrate salt was used as a source of cadmium ions, many growth parameters have been considered in this work to specify the optimum conditions, namely (cadmium ion concentration, deposition time, temperature of solution and pH value).The structure, optical and electrical properties of CdO films are investigated and analyzed extensively with respect to growth conditions. Annealing in air at different temperatures (548, 573, 598, and 623k) at constant time of (15min.), X-Ray diffraction technique has confirmed the formation of cadmium oxide (CdO), and proved that the optimum deposition conditions which produce pure phase of CdO are through molarity of nitrate 0.2M, 80C°, pH=9 and at deposition time of 30min. The average grain size increases with annealing process due to relaxation in the tensile strain for deposition films. High quality films are achieved by adding KCN solution, leading to increasing in average grain size, transmission, and electrical conductivity from 16nm, 75%, and 88 (Ω.cm)-1 to 36nm, 85%, and 365(Ω.cm)-1 respectively after KCN solution added. The values of thermal activation energies in low and high temperature regions could be altered with deposition conditions, where changed from 0.1532eV and 0.2825eV to 0.2910eV and 0.3650eV respectively after KCN added to the preparation solution. The CdO film has two values of activation energies as a result of polycrystalline structure. The CdO film which was deposited by bath contain to the KCN solution, the concentration and mobility of carriers reach to values of 4.5*1019 cm-3 and 50.69 cm2/V.sec respectively.

Abstract

In this work magnetic water was prepared and its properties were studied. Also CaCO3 and CaC2O4 solutions characteristics were studied, which represent the basic components to form scales in the equipments and systems that are in touch with water, calcium oxalate also forms kidney stone. The magnetic field that was used was supplied by electrical magnets, where the magnetic field values were between (0.06-1T), at exposure time of magnetic field (5-35 min). In the first stage of research, tap water was exposed to a magnetic field between (0.06-0.4T) with exposure time ranging between (5-35min). After studying the characteristics of exposed tap water, it was found that the pH value was increased from (7.2 to 7.6) and the conductivity increased from 700(µs/cm) to 725(µs/cm), TDS values also increased from 300 to 340 (ppm), while surface tension was decreased from 0.073 to 0.058 N/m. The second stage of research covers some characteristics of calcium carbonate solution, also morphology and nature of its scales using optical microscope. It was found that after exposing tap water to the magnetic field, pH value were increased from 7.7 to 7.86 and conductivity increased from 140 to 170 (µs/cm), while TDS values were increased from 50 to 80 (ppm). Morphology of calcium carbonate was observed after, exposing it to magnetic field. It was found that the scale was light little adhesion to surface. The third stage of this research deals with calcium oxalate solution, after exposing it to the magnetic field varying from (0.3 to 1)T and exposing time (5-30 min). It was found that the conductivity increased from 50 to 100(µs/cm), TDS values were increased from 50 to 85(ppm).The morphology of CaC2O4 precipitates after magnetic treatment was smooth with little adhesion to surface. Finally it was concluded that the magnetic treatment reduces the scales in the instruments and also has good medical advantages.

Abstract

This study was performed by using Phenol-Formaldehyde Resin Type (Novolac) as basic material for the composite material and added to (14%) of the Hardened hexamine tetra mine (HMTA) while the granules of Iraqi oil coal as a supporting material. Samples were prepared in two different percentages of the Reinforcement material (Iraqi oil Coal) in (5%) and in (10%) . After that a study was performed for some of the physical characteristics of the samples and a comparison was made between the results obtained from them. The mechanical characteristics which were studied were represented by the bending test and the impact test. Also the dispersion factor was calculated after submerging the samples simultaneously for a defined period of time in each of distilled water and kerosene and generally the result showed regarding the mechanical the mechanical characteristics. The increase of these characteristics for the mixing percentage determined by (10%) and these two percentages were taken as basis not to concentrate on them in the previous researches and at these two percentages and as follows: In the bending test the module of Elasticity (E) were greater in the percentage of coal amounting (5%) and around (1.024 kn/m2) compared with (0.57 – 0.326 kn/m2) At the mixing percentage amounting (10%). And for the impact test also the impact resistance ranged between (2.24 kj/m2) For the mixing percentage amounting (5%) from the mixing percentage amounting (10%) which ranges between (1.52 kj/m2 – 1.44 kj/m2). In the permeability and dispersion test the samples of mixing percentage amounting (10%) for the oil coal showed resistance to dispersion weaker than the samples of mixing percentage amounting (5%) in kerosene and water respectively.

Abstract

The oxidation of carbon monoxide CO over supported noble metal catalyst is an important part of the catalytic control in sealed-off TEA CO2 laser system. Despite the large number of researches dealing with the subject, kinetics of reaction is still unsettled. However, this project falls into three parts focused on oxidation CO to CO2 over supported noble metal catalysts: The first part is to determine the activity of supported noble metal catalysts (i.e. Pt/Al2O3, Pd/Al2O3) in removal CO as CO2 gas phase, and study the effect of reaction rate parameter k (sec ) on conversion processes of CO to CO2 at =2500 (sec) by using model of first order reaction at isothermal conditions. The second part is to calculate CO2 production rates for the steady state oxidation of CO over supported noble metal catalyst such as (Pt/Al2O3) in mathematical models at temperature T=473(K) and pressure p=1(atm) that produce for Herz & Marin model-I and for Herz & Marin model-II. Then they are compared with Langmuir-Hinshelwood-Hougen-Watson rate, which is about . Also, these results improve first order reaction in CO2 at low concentration of CO. The effect of temperatures range (476K to 570K) on CO2 rates ( ) was also investigated and shows the same behavior of first order reaction in CO2. Finally, according to the results of CO2 production rates ( ) of Herz & Marin model-I and II, the volume of catalyst ( ) was calculated by using the numerical evaluation of integral space time ( ) at constant volume (i.e. dv/dt=0) and volumetric flow rate Q=10(cm . sec ) which give a technological path to design catalyst reactor in sealed-off CO2 laser system for the experimental part.

Abstract

The effect of laser to killing & inactivate wounds bacteria has been studied, in order to using it as an active method for sterilization & treatment. To achieve that, two types of pathogen wounds bacteria were used, which isolated from the wounds patients at Al – kindee hospital , they were : Staphylococcus aureus & Pseudomonas aeruginosa . Photosensitization technique was applied as a method for bacterial killing using Toludine blue – O (photosensitizers) conjugated with three types of lasers that emitted in the visible region of the electromagnetic spectrum:  Argon laser with power of 150 mW , and wavelength of 514 nm , was used at the first time for bacterial killing field by photosensitization technique.  Nd:YVO4 laser with power of 10 mW , and wavelength of 532 nm, was used at the first time for bacterial killing field by photosensitization technique.  He – Ne laser , with power of 5 mW , and wavelength of 632.8 nm. Bacteria were irradiated after spread it on the nutrient medium (blood agar) by using four concentrations of the photosensitizer Toludine blue – O (0.01 , 0.05 , 0.1 ,0.2)% (w/v) at 1 cm & 50 cm (distance from the irradiation source) , for S . aureus. For P. aeruginosa and mixture of two bacteria , the concentrations using were reduced to 0.01 , 0.05 , 0.1 % (w/v) , and the distance between the irradiation source and the sample was choosed as 50 cm only . All of samples were irradiated without using the Toludine blue – O (0.0 % (w/v)) . The irradiation results revealed appearance of a clear bacterial killing regions equivalent to laser spot size diameter (and more of that) when the two types of bacteria and their mixture were irradiated by Argon laser at all dyes concentrations & all irradiation periods which range 1 , 2 , 3 , 4 , 8 minutes by comparison with the Nd:YVO4 and He – Ne lasers . Bacterial killing regions were obtained when S . aureus bacteria were irradiated by Argon laser for 1 minute at 0.01 % (w/v), whereas bacterial killing regions were noticed during irradiating for 8 minutes by He – Ne laser & for 12 minutes by Nd:YVO4 laser using 0.05 % (w/v) at 1 cm & 50 cm (from the irradiation source and the sample) . In addition , Bacterial killing regions were equivalent to laser spot size diameter (and more of that) were obtained when the tow types of bacteria and their mixture irradiated by Argon laser without using the Toludine blue – O (laser alone) , whereas no any Bacterial killing regions appeared when they irradiated by Nd:YVO4 & He – Ne lasers alone (without using photosensitizer) even the period irradiation reached to 15 minutes. On the other hand , the 0.1 % (w/v)concentration of Toludine blue – O dye was considered as an ideal concentration, when it using as a photosensitizer conjugated with laser light to form the photochemical reaction , because the Bacterial killing regions were noticed for all treatments with three types lasers irradiations and for all irradiation periods . In this study , increasing of P. aeruginosa bacteria sensitivity to killing by photosensitization technique were revealed , by the comparison with the S . aureus bacteria when using the Toludine blue – O dye conjugated with three types of lasers, the best diameter for bacterial killing were obtained about 6 mm when P. aeruginosa bacteria were irradiated by Argon laser for 3 minutes by using 0.1 % (w/v) of the photosensitizer, whereas bacterial killing diameter was about 5 mm when S . aureus bacteria irradiated by Argon laser for 4 minutes by using the same photosensitizer concentration . On the other hand, the results were revealed that there is no a clear differences of Bacterial killing regions formation when S . aureus bacteria were irradiated at 1 cm or 50 cm (the distance between the irradiation source and the sample) .

Abstract

Construction of Pulsed Laser Ablation (PLA) system has been carried out. Nd:YAG pulsed laser has been employed to prepare silicon films constituting silicon nanoparticles. Various laser parameters were examined to produce films of different properties such as the laser energy, laser fluence, number of pulses and the targetsubstrate distance. We have studied the optical, structural and some electrical properties of the deposited films. Optical properties were included like the transmission, absorption, electronic and photoluminescence while a study on the structural properties was carried out using x-ray diffraction and the film morphology. Moreover, J-V characteristic in the dark and under light illumination have been conducted to study some of the film electrical properties. Our experimental data have been fitted with the theoretical quantum confinement model to analyze the photoluminescence curves and estimate the nanoparticle sizes and their distribution. From the optical transmission studies, we have found that the band gap of the nanostructured films lies between (1.5 – 2.4) eV due to the existence of various nanoparticle sizes in the deposited film. Furthermore, the photoluminescence (PL) spectra indicate that the estimated band gap lies between (1.6 – 2.4) eV. The corresponding nanoparticle sizes contributing the PL emission is in the range (22 – 38) A°. These results were found to be inconsistent with that obtained by the x-ray analysis. Finally, it was observed that the film morphology is significantly affected by the laser fluence and the target-substrate distance. Therefore, one could prepare various films suitable for different applications.

Abstract

The project involved the preparation of two-polymer blends of Poly-Propylene (PP), and high impact polystyrene (HIPS) in different proportions (50-100)% with the aim of arriving at the best physical blending percentage. For this purpose, a single-screw extruder is used in test-sample preparation, followed by hot-press several plates extruded along opposite directions. In order to study the influence of blending on the mechanical properties and some physical properties, several tests are performed included (tensile, compression, bending strength, impact resistance, creep and relaxation time, thermal conductivity, and dielectric constant, diffusion test using alkaline(KOH), acidic(HNO3), and saline(CaCl2) solution, in addition to optical microscopy and thickness measurement of extruded plate-samples ). Longitudinal and transverse tensile tests are performed for the extruded test-samples while for pressed - plate samples only longitudinal tensile test is done. In both cases, results reveal that the best blending percentage is (80/20)%(PP/HIPS), derived from tensile and ultimate stress when compared with those for pure pressed materials. Test results of extruded test samples show elongation percentage improvement with improved mechanical properties . From the calculations of modulus of elasticity for tensile, bending and compression, and from hardness tests, the best blending percentage is (70/30)%(PP/HIPS), also at this blending percentage, the greatest creep rate and relaxation times are realized. Impact resistance results show that for all blending percentages are lower than that for pure (HIPS), with some improvement for the blending percentages (50/50)%, (60/40)%, (90/10)% of (PP/HIPS) as compared to pure polypropylene. Thermal conductivity results are found to vary between those for pure polypropylene and high-impact polystyrene except for the blending percentages (70/30)% and (90/10)% (PP/HIPS) which appear higher. Dielectric tests reveal that the dielectric constant, in general, shows higher value than that for pure polypropylene and high-impact polystyrene . Diffusion coefficient tests results show the highest obtained value is for the (60/40) % and (50/50) % (PP/HIPS) blends, while for the other blend percentages it varies between that for polypropylene and high-impact polystyrene with some apparent improvement due to the effect of chlorides on the blends except of the (50/50)%(PP/HIPS) blend. Thickness measurements reveal that plate thickness increases with increase of (HIPS) percentage, with gradual decrease in brightness of samples, greatest brightness is observed in the (90/10)%(PP/HIPS) blend. Pure polypropylene appears transparent. Optical microscopy shows increase in crystallinity with gradual increase in nucleation reaching nucleation in high-impact polystyrene.

Abstract

In this research, Nickel Sulphide thin films have been prepared by Spray Pyrolysis deposited on thin glass substrate at 513±278kº to study their structural, optical & electrical properties, Nickel Sulphide thin films have been prepared by using 0.05M Nickel Chloride aqueous solution & Thioria aqueous 0.05 M. The effect of annealing on thin films at 350Co temperature & time of 60min was also studied. The results of (X – ray) diffraction showed that NiS thin films have amorphous structure, but the annealed films started to have a polycrystalline structure. Optical microscope showed that the annealing of films had reduced the surface deformation. The optical measurements show that the films have relatively high absorption coefficient(1.8×105cm-1) at wavelength from 950nm up to 1200nm & the absorption coefficient reduce with the annealing (1.05×105cm-1). The energy gap was increase when the films annealed from(1.05)eV up to)1.16)eV for the direct–allowed transition and from(0.99)eV to (1.06)eV for the an-allowed transition and(0.96)eV to(1.045)eV for an direct–allowed transition an from(0.9)eV to(1.0(1eV for an-allowed-in direct transition. Through studying the electrical conductivity, it has been found that it decreases with annealing at temperature of 623ko, the activation energy for un-annealed thin film was (0.7eV) but after annealed it was (0.8eV). Seebak effect showed that all films are P–type for the annealed and un-annealed films.

Abstract

An analytical study of spectral lines (in soft x-ray region) of laser produced plasma (LPP) is carried out. The work is concentrated on two main points, firstly: studying of the opacity broadening of spectral lines and secondly: studying the escape factor of photons. The opacity broadening and escape factor are studied for Al, C, Mg, Si, Ge and LiF plasmas, the selected wavelengths was (6–35 Å) which have a lot of applications in many fields such as biological applications (x-ray microscopy), integrate circuit industry , x-ray laser , x-ray source etc . The opacity broadening is studied as a function of plasma size and plasma density, the effect of the difference between energy levels of emission spectral lines on opacity of plasma is also studied. The escape factor which represents the probability of photons to escape from plasma is studied as a function of opacity. From our results that have been obtained one can notice that the opacity of plasma increases with increases in size and density of plasma, atomic number of target and also it is increases with decreases the difference of energy between energy levels of spectral lines. We notice also that the escape factor is increases with decreases the opacity, where the escape factor of spectral line of higher series member transitions is very large compare with the escape factor of spectral line of lower series member transitions ,and also we found that the escape factor is decreases with increases the atomic number of the target .

Abstract

In this research, Copper Sulphide thin films have been prepared by spray pyrolysis to study their structural , optical & electrical properties by using 0.1M Copper nitrate aqueous solution & Thioria aqueous 0.1M & 0.4M . The films were doped with Aluminum by 1%, 2%, 3% ratios. In addition to this the effect of annealing on the undoped thin films at 200Co temperature & different times of 60min. & 120min. were investigated . The results of ( X – ray ) diffraction showed that the doped and undoped have amorphous structure , but the annealed films start to have a polycrystalline structure . The films prepared with a low ratio of Thioria have a high amounts of Chalcocite phase. Optical microscope showed that the annealing & doping of films had reduce the surface deformation. The optical measurements show that the films with low ratio of Thioria have relatively high absorption coefficient & the absorption coefficient increase with the doping ratio & reduce with increase the Thioria concentration & annealing time. The allowed direct energy gap was reduced with doping & increase when the films annealed. Through studying the electrical conductivity, it has been found that it increase with increasing of doping ratio & decreases with annealing at temperature of 200Co . But Thioria concentration is the mean operator acting in the electrical conductivity where conductivity increase with increasing Thioria concentration. Seebak effect showed that all films are P - type.

Abstract

The number buildup factor (B.U.F) for two source and 1.012 mCi (37.444 MBq) and 1.304 mCi (48.248MBq) using scintillation detector (3"×3") NaI(Tℓ) to the Iraqi powders of black carbon (B.C) and graphite after mixing with remnant binder material (epoxy risen) with mixing ratios 40% and 50% ,were studied in this research. Four cylindrical shields were made with diameter of 6.2cm, two from black carbon (B.C) with mixing ratio 40% and 50% and another two from graphite, with thickness between (0.5-7.58)cm for each shields .the linear attenuation coefficients and buildup factor were calculated. Empirical equations (Capo, Berger, Power, Taylor, and Exponential) were used to fit the experimental buildup factor data. The fitting were successful with equations (Capo, Berger, Power) and the Average Percentage Diversion estimated to be (0.16% , 0.21%, 0.22%) respectively, large diversion were noticed when (Taylor, Exponential) equations been used with A.P.D (0.36% , 0.71%) respectively. The result illustrating that the buildup factor with energy 1.25 MeV for black carbon and graphite (40% and 50%) with thickness between (0-0.5398 ) and (0-0.7541) m.f.p respectively, highly depends on the mixing ratios, bulk density and type of material. Reductions in buildup factor values were noticed with increasing the mixing ratios, bulk density. Moreover the buildup factor values for black carbon found to be higher than that for graphite. Result also shows, that the buildup factor with energy 0.662 MeV for both black carbon and graphite with 50% mixing and thickness rang between (0-8421) m.f.p , a little increase for black carbon of thickness . No effect for mixing ratios, bulk density and type of material were noticed at this energy. There is an increased in buildup factor values when the radiation energy increased.