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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: 4Effect of Yttrium Solubility on the Structural and Optical Properties of Bi1.5-x< Pyrochlore Ceramics(Elsevier Sci Ltd, 2013) Qasrawi, A. F.; Mergen, A.In this article, the yttrium solubility effects on the structural, dielectric and optical properties of the Bi1.5-xYxZn0.92Nb1.5O6.92 (Y-BZN) solid solutions are investigated. The yttrium content (x) was varied in the range of 0.04-0.6. The scanning electron microscopy and energy dispersion analysis have shown that the single phase of the yttrium doped pyrochlore is possible up to yttrium content of 0.06. At x=0.07 YNbO4 minor phase appears and at x=0.08 YNbO4 and ZnO dominates in the Y-BZN. Due to the very rare amount and the random distribution of the minor phases in the pyrochlore, the X-ray diffraction technique was not able to detect these minor phases at low yttrium doping levels. While the nonstoichiometric phase evaluated at x=0.07 displayed no role on the relative density, the dielectric constant, dielectric loss, the temperature coefficient of dielectric constant, the absorbance and the energy band gap are observed to be sharply altered. The energy band gap of the pure BZN widened from 3.30 eV to 3.60 eV when the BZN was doped with Y content of 0.04. It then sharply shrunk to 2.75 eV for Y content of 0.07. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
