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Öğe Effect of Al0.1Ga0.9As thickness on the structural, optical, thermal, and electrical properties of (Al0.1 Ga 0.9As)/GaAs heterojunctions(Elsevier Ltd, 2023) Al-Naghmaish, Aishah; Ghrib, Taher; Dakhlaoui, H.; AL-Saleem, N.K.; Ercan, F.; Kayed, Tarek S.; Elibol, ErdemAl0.1Ga0.9As nano-films of various thicknesses were deposited on GaAs substrate and examined using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), UV–Visible spectrophotometry, Photoluminescence (PL), Electrochemical Impedance Spectroscopy (EIS), and Photothermal Deflection (PTD). The PTD technique is used to analyze the effect of Al0.1Ga0.9As thickness on thermal properties and showed its sensitivity to weak structural changes. By increasing the Al0.1Ga0.9As thickness, the crystallinity was degraded, an infrared emission centered at 997.4 nm whose intensity is the highest for 50 nm was observed. A pn junction was formed for thicknesses higher than 400 nm, the band gap was increased from 1.59 to 1.68 eV. The thermal conductivity increased from 35.3 to 37.3 W m? 1 K?1 and the thermal diffusivity increased from 0.195 to 0.22 cm2 s?1. As a result of this investigation, the Al0.1Ga0.9As/GaAs can be considered for potential applications in photoelectric and thermoelectric devices. © 2023 The Author(s)Öğe Investigation of structural, spectroscopic, dielectric, magnetic, and in vitro biocompatibility properties of Sr/Ni co-doped hydroxyapatites(Elsevier Sci Ltd, 2022) Ercan, Filiz; Kayed, Tarek S.; Kaygılı, Ömer; Bulut, Niyazi; Almohazey, Dana; Ateş, Tankut; Al-Ahmari, Fatimah SaadIn this study, the changes caused by Ni and Sr additives on the structural, thermal, dielectric, and magnetic properties of hydroxyapatite (HAp) samples were examined and reported for the first time in detail. Some effects of the Sr/Ni site disorder on the crystallographic, dielectric, and magnetic properties in Sr/Ni-HAp have been examined, as well as their cytotoxicity effects. The addition of Ni affected the morphology of nanoparticles with a low agglomeration increase. Our results showed that the dielectric constant (epsilon') and dielectric loss (epsilon '') have greater values at low frequencies than at higher frequencies for all the samples. It can be concluded that Ni and Sr additions to the HAp structure contribute to the development of thermal, magnetic, and dielectric properties required to mimic natural HAp in the study conducted with the idea of creating a medical application area for bone healing and regeneration. The cytotoxicity test of the produced nanoparticles and the evaluation of the results were also performed using human foreskin fibroblasts (HFF). The viability of cells after treatment for 48 h ranged between 50 and 75%. While 0.37Ni-0.37Sr-HAp and 1.11Ni-0.37Sr-HAp were similar to 0.37Sr-HAp, 0.74Ni-0.37Sr-HAp had the highest cellular viability. At 0.1 mg/mL, 0.74Ni-0.37Sr-HAp had a viability of 79.97% compared to the untreated control cells. Our Sr/Ni-HAp nanoparticles have promising medical applications in bone healing and regeneration.Öğe Photoconductivity kinetics in AgIn5S8 thin films(Elsevier Science Sa, 2010) Qasrawi, A.F.; Kayed, Tarek S.; Ercan, İsmailThe temperature (T) and illumination intensity (F) effects on the photoconductivity of as grown and heat-treated AgIn5S8 thin films has been investigated. At fixed illumination intensity, in the temperature region of 40-300K, the photocurrent (I-ph) of the films was observed to decrease with decreasing temperature. The I-ph of the as grown sample behaved abnormally in the temperature region of 170-180K. At fixed temperature and variable illumination intensity, the photocurrent of the as grown sample exhibited linear, sublinear and supralinear recombination mechanisms at 300 K and in the regions of 160-260K and 25-130 K. respectively. This behavior is attributed to the exchange of role between the linear recombination at the surface near room temperature and trapping centers in the film which become dominant as temperature decreases. Annealing the sample at 350 K for 1 h improved the characteristic curves of I-ph. The abnormality disappeared and the I-ph - T dependence is systematic. The data analysis of which revealed two recombination centers located at 66 and 16 meV. In addition, the sublinear recombination mechanism disappeared and the heat-treated films exhibited supralinear recombination in most of the studied temperature range. (C) 2010 Elsevier B.V. All rights reserved.Öğe Structural, magnetic and gamma-ray shielding features of cerium doped Mg2FeTiO6 double perovskite(Elsevier, 2023) Saleh, Noha A.; Alqahtani, Muna Y.; Mhareb, M. H. A.; Ercan, Filiz; Ghrib, Taher; Kayed, Tarek S.; Özçelik, BekirThe Mg2FeTi1-xCexO6 [ x = (0, 2, 4, 6, 8, 10)%] ceramics with different Ce concentrations have been pre-pared by solid-state technique. That compounds were doped with cerium dioxide (CeO2) to develop new material for gamma radiation shielding. The prepared nanomaterials were analyzed to investigate their structural and optical properties by XRD, FTIR, SEM, magnetic properties, and UV techniques. It was de-termined by the XRPD method that the atomic and molecular structures of Ce-doped compounds were in the tetragonal crystal system and crystallized in the P4/mmm (No: 123) space group. The refinement parameters of the compound Ce doped x = 8% were gof 2.4 and Rf 0.82. The effect of the Ce doping on the magnetization was measured in the magnetic field ranging at +/- 10 kOe for two temperatures (300 and 10 K) and showed that its Saturation Magnetization (Ms) was increased with the doping increase from 6.2 to 8.1 and from 14.7 to 18.7 for the temperatures 300 and 10 K, respectively. Various radiation shielding parameters for gamma-rays, neutron, and proton were evaluated using Phy-X and SRIM soft -wares. The linear attenuation coefficient (LAC) increases gradually with adding CeO2 to Mg2FeTiO6 from 54.290 to 92.032 cm -1 at 0.015 MeV. Also, fast neutron removal cross-section ( ER ) rises from 0.077 to 0.115 cm-1 for x = 0 and x = 10%. While the sample x = 10% shows the lowest projectile range for pro-tons. This sample considers the best sample to stop protons. The Analysis demonstrates that the sample with x = 10% shows the highest gamma, proton, and neutron shielding properties nominated it to use in radiation shielding field.(c) 2022 Elsevier B.V. All rights reserved.Öğe Structural, optical, and electrical investigation of multilayered MnO2(n)/ NiO(p) heterojunctions for supercapacitors applications(Elsevier, 2023) Alanazi, Maha; Ghrib, Taher; Ercan, Filiz; Alsubaie, Mizna; Demirci, Tuna; Kaygili, Omer; Kayed, Tarek S.Heterojunctions of alternating MnO2 and NiO thin films were deposited on an Indium Tin Oxide (ITO). The MnO2 and NiO thin films were synthesized by electrodeposition and sol-gel methods respectively. The structural morphology of the synthesized heterojunctions was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The microstructural and chemical compositions were examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Raman techniques. The optical properties were investigated by Ultraviolet-Visible (UV) analysis. The electrical conductivity, specific capacitance, and charge carrier density were determined using the Hall effect and Electrochemical impedance spectroscopy (EIS) methods. As a result, it was found that the MnO2 and NiO thin films crystallize in tetragonal and cubic crystal systems respectively. Increasing the number of NiO/MnO2 heterojunctions increases the electrical conductivity from 9.7 x 10- 7 to 1.2 x 10-3 S.cm- 1, the bandgap decreased 3.16 to 2.62 eV, the volume carrier density rises from 5.17 x 1011 to 4.62 x 1012 cm-3. The specimens constituted of two and four alternative staked MnO2 and NiO layers are characterized by a specific capacitance of 3.6 x 103 and 5.8 x 103 F.g -1 and capacitance retention of 14.8 and 12.9% which consider them promising materials for supercapacitor devices.
