5 results
Search Results
Now showing 1 - 5 of 5
Article Citation - WoS: 4Citation - Scopus: 4Physical Properties of Neodymium Tin Oxide Pyrochlore Ceramics(de Gruyter Poland Sp Zoo, 2017) Saleh, Adli A.; Qasrawi, A. F.; Yumusak, G.; Mergen, A.In this work, physical properties of neodymium tin oxide pyrochlore ceramics prepared by solid state reaction technique are investigated by means of X-ray diffraction, scanning electron microscopy, ultraviolet-visible light (UV-Vis) spectrophotometry and temperature dependent electrical resistivity measurements. The pyrochlore is observed to have a cubic FCC crystal lattice with lattice parameter of 10.578 angstrom. The planes of the cubic cell are best oriented in the [2 2 2] direction. From the X-ray, the UV-Vis spectrophotometry and the electrical resistivity data analysis, the grain size, strain, dislocation density, optical and thermal energy band gaps, localized energy band tail states and resistivity activation energies are determined and discussed. The pyrochlore is observed to have an optical energy band gap of similar to 3.40 eV. This value corresponds to 365 nm UV light spectra which nominates the neodymium tin oxide pyrochlore ceramics for the use as UV sensors.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: 4Electrical Conductivity and Capacitance Spectra of Bi1.37sm0.13< Pyrochlore Ceramic in the Range of 0-3 Ghz(World Scientific Publ Co Pte Ltd, 2014) Qasrawi, A. F.; Bzour, Faten M.; Nazzal, Eman O.; Mergen, A.In this work, the electrical properties of samarium-doped bismuth niobium zinc oxide (Sm-doped BZN) pyrochlore ceramics are investigated by means of temperature dependent electrical conductivity and capacitance spectroscopy in the frequency range of 0-3 GHz. It was observed that the novel dielectric Sm-BZN ceramic exhibits a temperature and electric field dependent dielectric breakdown. When measured at 300 K, the breakdown electric field is 1.12 kV/cm and when heated the breakdown temperature is similar to 420 K. The pyrochlore is thermally active above 440K with conductivity activation energy of 1.37 eV. In addition, the room temperature capacitance spectra reflected a resonance-antiresonance switching property at 53MHz when subjected to an AC signal of low power of 5 dBm. Furthermore, when the Sm-BZN ceramics are used as microwave cavity and tested in the frequency range of 1.0-3.0 GHz, the cavity behaves as low pass filter with wide tunability up to a frequency of 1.91 GHz. At this frequency it behaves as a band rejection filter that blocks waves of 1.91 GHz and 2.57 GHz frequencies. These properties of the Sm-doped BZN are promising as they indicate the usability of the ceramics in digital electronic circuits as resonant microwave cavities suitable for the production of low pass/rejection band filters.Article Citation - WoS: 1Citation - Scopus: 1Tungsten Doped Bi1.5zn0.92< Ceramics Designed as Radio/Microwave Band Pass/Reject Filters(Wiley, 2021) Qasrawi, Atef F.; Abdalghafour, Mays A.; Mergen, A.Herein, radiowave/microwave bandpass/reject filters are fabricated from the tungsten doped Bi1.5Zn0.92Nb1.5-6x/5WxO6.92 (W-BZN) pyrochlore ceramics. The W-BZN band filters are prepared by the solid state reaction technique and subjected to X-ray diffraction (XRD) and impedance spectroscopy analyses. It was shown that the W-BZN filters can display negative capacitance effects accompanied with resonance-antiresonance oscillations. The calculations of the reflection coefficient parameter (S-11), the return loss (L-r) and the voltage standing wave ratios (VSWR) in the frequency domain of 0.01 to 1.80 GHz, has shown that the W-BZN device can perform as microwave cavities at two notch frequency values of 0.44 and 1.53 GHz. W-BZN devices can also be nominated as noise reducers and radiowave/microwave signal receivers suitable for telecommunication technology.Article Citation - WoS: 4Citation - Scopus: 5Electrical Characterization of Bi1.50-x< Varactors(World Scientific Publ Co Pte Ltd, 2014) Qasrawi, A. F.; Abu Muis, Khalil O.; Abu Al Rob, Osama H.; Mergen, A.The electrical properties of yttrium doped bismuth zinc niobium oxide (BZN) pyrochlore ceramics are explored by means of temperature dependent electrical conductivity dielectric constant and capacitance spectra in the frequency range of 0-3 GHz. It is observed that the doped BZN exhibit a conductivity type conversion from intrinsic to extrinsic as the doping content increased from 0.04 to 0.06. The thermal energy bandgap of the intrinsic type is 3.45 eV. The pyrochlore is observed to exhibit a dielectric breakdown at 395 K. In addition, a negative capacitance (NC) spectrum with main resonance peak position of 23.2 MHz is detected. The NC effect is ascribed to the increased polarization and the availability of more free carriers in the device. When the NC signal amplitude is attenuated in the range of 0-20 dBm at 50 MHz and 150 MHz, wide tunability is monitored. Such characteristics of the Y-doped BZN are attractive for using them to cancel the positive parasitic capacitance of electronic circuits. The canceling of parasitic capacitance improves the high frequency performance of filter inductors and reduces the common mode noise of the resonance signal.
