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Article Citation - WoS: 11Citation - Scopus: 12Structural, optical, electrical and dielectric properties of Bi1.5Zn0.92Nb1.5-xNixO6.92-3x/2 solid solution(Taylor & Francis Ltd, 2012) Qasrawi, A. F.; Nazzal, E. M.; Mergen, A.The effects of Ni content on the structural, optical, dielectric and electrical properties of Bi1.5Zn0.92Nb1.5O6.92 pyrochlore ceramics have been investigated. Nickel atoms were inserted into pure samples in accordance to the composition Bi1.5Zn0.92Nb1.5-xNixO6.92-3x/2, with x varying from 0.07 to 0.40. The structural analysis revealed that a single phase of the pyrochlore compound can be obtained for x values of 0.07 and 0.10 only. Further increase in Ni caused the appearance of multiple phases. The optical energy band gaps are determined as 3.30, 3.35 and 3.52 eV for Ni content of 0.00, 0.07 and 0.10 respectively. The temperature dependent electrical resistivity and the frequency dependent capacitance are observed to increase with increasing Ni content. The resonance frequency, which was determined from the capacitance-frequency dependence, was observed to shift from 12.14 to 10.47 kHz as the x values increase from 0.00 to 0.10 respectively.Article Citation - WoS: 3Citation - Scopus: 3Effect of Ionic Substitution on the Structural, Dielectric and Electrical Properties of Bismuth Zinc Niobate Ceramics(Korean Assoc Crystal Growth, inc, 2012) Qasrawi, A. F.; Abu Je'ib, Hussein A.; Mergen, A.; Department of Electrical & Electronics EngineeringThe effects of tin substitution on the structural, dielectric and electrical properties of the Bi1.5Zn0.92Nb1.5O6.92 pyrochlore ceramics have been investigated. Tin atoms was substituted in the A (Bi1.5Zn0.46)-site instead of zinc and in the B ((Zn0.46Nb1.5)-site instead of niobium in accordance to the chemical formulae Bi1.5Zn0.92Nb1.5-xO6.92-x/2 and (Bi1.5-x/3Zn0.46-3x/2Snx)(Nb1.5Zn0.46)O-6.92, for 0.00 <= x <= 0.40 and 0.00 <= x <= 0.60, respectively. A relative single phase formation of the structures was possible for x values less than 0.25 and less than 0.10. Pronounced tunability in the dielectric constant values associated with very low dielectric loss are obtainable by Sn substitution. Furthermore, a frequency invariant but linearly varying temperature dependent dielectric constant is observed. The electrical conductivity decreased by two and one order of magnitude for the A and B-site substitutions, respectively. The temperature-dependent conductivity analysis in the temperature region of 300-500 K, reflected the existence of shallow and deep impurity energy levels being created by the doping process.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: 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.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: 1Cobalt Doping Effects on the Mechanical and Electrical Parameters of Bi1.5zn0.92< Solid Solution(indian Ceramic Soc, 2014) Qasrawi, A. F.; Jaradat, Haneen N. M.; Mergen, A.The cobalt doping effects on the lattice constant, strain, grain size, dislocation density and electrical conduction are investigated by means of X-ray diffraction and electrical resistivity measurements on the Bi1.5Zn0.92Nb1.5-xCoxO6.92-x (x=0.03-0.20) ceramics, respectively. Increasing cobalt content sharply increases compressing strain and dislocation density and decreases both the lattice constant and the grain size of the pyrochlore. At a doping content of 0.05 new minor phase of ZnO appears. The ZnO grains increase with increasing cobalt content. When the cobalt doping is repeated in accordance with the formula Bi1.5Zn0.92Nb1.5-xCoxO6.92-x, a single phase pyrochlore is obtained with cobalt content up to 0.10. The electrical resistivity analysis reflects increasing activation energy with increasing cobalt content. The cobalt creates an impurity level in the energy gap of the pyrochlore that shifts towards the mid gap converting the extrinsic nature of conductivity to intrinsic at a cobalt content of 0.10.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: 5Citation - Scopus: 6Mechanical and Electrical Properties of Bi1.5-xlax< Pyrochlore Ceramics(Springer, 2016) Qasrawi, A. F.; Kmail, Renal R. N.; Mergen, A.; Genc, SevalThe physical properties of Bi1.5-xLaxZn0.92Nb1.5O6.92 solid solutions are investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion X-ray spectroscopy (EDS), and temperature dependent relative permittivity and electrical resistivity measurements. The La content which was varied from 0.10 to 0.60 is found to be solvable up to 0.21. Further increase in the amount of the La content caused the appearance of Bi0.4La0.6O1.5, LaNbO4, and ZnO minor phases in the pyrochlore matrix. While the lattice parameter and the theoretical, bulk and relative density are hardly affected by the increase in the La content, the strain, the dislocation density and the crystallite size are remarkably varied. The relative permittivity and temperature coefficient of relative permittivity are found to be sensitive to the La-Content. The electrical resistivity is observed to be temperature invariant below 390 K. It exhibits an insulator-semiconductor transition property at a critical temperature that increases with the increasing La content. Such observation is assigned to the increase in the dislocation density, which arises from the increment in the La content. The activation energies of the doped ceramics, which are determined from the electrical resistivity analysis are found to be similar to 1.12-1.00 eV.Article Citation - WoS: 3Citation - Scopus: 3Investigation of the Physical Properties of Bi1.5-xcdx< Pyrochlore Ceramics(Springer, 2013) Qasrawi, A. F.; Kmail, Bayan H.; Nazzal, Eman M.; Mergen, A.For the purpose of dielectric parameters tuning Bi1.5Zn0.92Nb1.5O6.92 (BZN) pyrochlore ceramics were subject to cadmium doping in accordance to the chemical formula; Bi1.5-xCdxZn0.92Nb1.5O6.92-x/2 for 0.10 a parts per thousand currency sign x a parts per thousand currency sign 0.50. The main physical properties of the doped samples were investigated by means of X-ray diffraction, scanning electron microscopy associated with energy dispersion spectroscopy, temperature dependent dielectric constant and temperature dependent electrical resistivity to obtain the crystalline structure, the lattice parameter, the relative density, the surface morphology and chemical composition. Optimization of single phase Cd doped samples were possible for x a parts per thousand currency signaEuro parts per thousand 0.14, beyond this limit, ZnO and Zn3Nb2O8 minor phases grow through the structure of the BZN. For samples which exhibit single BZN phase, the dielectric constant, the electrical resistivity and the resistivity activation energy increased with increasing Cd content. The maximum obtainable dielectric constant as 259 and 224 with high signal quality factor of 690 and 1090 at 25 and 200 A degrees C, respectively, was for the sample doped with 0.14 Cd. These values are promising for implantation of BZN in RF and microwave technology as a resonator with high quality signal.
