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Article Citation - WoS: 3Citation - Scopus: 4Structural, Optical and Electrical Properties of Bi1.5zn0.92< Pyrochlore Ceramics(Univ Fed Sao Carlos, dept Engenharia Materials, 2021) Qasrawi, A. F.; Abdalghafour, Mays A.; Mergen, A.Herein, the structural, morphological, compositional, optical, electrical and dielectric properties of Bi1.5Zn0.92Nb1.5-6x/5WxO6.92 (BZN) solid solutions are reported. Tungsten substituted BZN ceramics which are fabricated by the solid state reaction technique exhibited solubility limits at substitution level below x=0.18. Remarkable engineering in the structural, optical, electrical and dielectric properties of the pyrochlore ceramics is achieved via W substitution. Namely, shrinkage in both of the lattice parameters and in the energy band gap accompanied with decrease in the microstrain, in the dielectric constant and in the electrical resistivity is observed upon increasing the W content below the solubility limit. The increase in the W content in the BZN ceramics enhances the densification of the pyrochlore and leads to higher light absorbability and larger crystallites growth. The temperature dependent electrical resistivity measurements has also shown that the pyrochlore exhibit thermal stability below 380 K.Article Citation - WoS: 4Citation - Scopus: 4Optical Dynamics at the Au/Znpc Interfaces(Univ Fed Sao Carlos, dept Engenharia Materials, 2020) Qasrawi, A. F.; Zyoud, Hadeel M.In this work, the optical dynamics and the structural properties of the zinc phthalocyanine which are coated onto 150 nm thick Au substrates are studied by the X-ray diffraction and optical spectrophotometry techniques. The Au/ZnPc interfaces appears to be strongly affected by the large lattice mismatches at the interface. It is observed that the coating ZnPc onto Au substrates increases the light absorbability by 4.7 and 128.2 times in the visible and infrared regions of light, respectively. Au substrates activated the free carrier absorption mechanism in the ZnPc thin films in the infrared range of light. In addition, the transparent Au substrates forced narrowing the energy band gap in both of the Q and B bands. It also increased the dielectric constant value by similar to 3.5 times in the IR range. The enhancements in the optical properties of ZnPc that resulted from the thin Au substrates make the ZnPc more suitable for optoelectronic, nonlinear optical applications and for electromagnetic energy storage in the infrared range of light.Article Citation - WoS: 4Citation - Scopus: 4Characterization of the Ge/Bi2< Interfaces(Univ Fed Sao Carlos, dept Engenharia Materials, 2019) Alharbi, Seham Reef; Qasrawi, Atef FayezIn this article, the properties of the Ge/Bi2O3 interfaces as microwave cavities are reported and discussed. The interface is composed of monoclinic Bi2O3 films grown onto polycrystalline cubic Ge substrate. It is observed that consistent with the theoretical design of the energy band diagram, the experimental current-voltage characteristics of the Yb/Ge/Bi2O3/C hybrid device structure exhibits electronic switching property. In addition, the capacitance, resistance and microwave cutoff frequency spectral analysis in the frequency domain of 0.01-1.50 GHz revealed a frequency dependent tunability of the device. Moreover, while the Yb/Bi2O3/C interface displays negative capacitance effect, the Yb/Ge/Bi2O3/C interfaces are also found to have the ability of altering the resistance up to three orders of magnitude. Such property allowed reaching a cut off frequency up to 116 GHz. The electronic features of the device indicated that the Ge/Bi2O3 interfaces are attractive for production of negative capacitance field effect transistors and band pass/reject filters.Article Citation - WoS: 3Citation - Scopus: 4Preparation and Characterization of Cdo/In6< Thin Film Transistors(Univ Fed Sao Carlos, dept Engenharia Materials, 2020) AlGarni, Sabah E.; Qasrawi, A. F.In this study, the design and characterization of CdO/InSe thin film transistors (TFT) that are grown onto Au substrates are investigated. The devices are also subjected to a vacuum annealing process at 300 degrees C to enhance the structure and electrical performance. It was observed that the growth of polycrystalline monoclinic In6Se7 phase of InSe is preferred at this annealing temperature when coated onto Au/CdO substrates. Electrically, noisy negative capacitance effect accompanied with resonance-antiresonance phenomena is observed in the capacitance spectra of the as prepared TFT devices. The annealing of the TFT devices reduced the noise in the capacitance, conductance, impedance, and reflection coefficient and return loss spectral responses. The heat treated TFT devices displayed low bandpass, high bandpass and bandstop filter characteristics in the studied frequency domain (0.01-1.80 GHz) indicating the applicability of these devices as radio wave-microwave resonators.
