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Article Citation - WoS: 3Citation - Scopus: 3Dielectric Dispersion and Energy Band Gap of Bi1.5-x< Solid Solution(Elsevier Science Bv, 2014) Qasrawi, A. F.; Mergen, A.The optical transmittance and reflectance spectra of samarium doped bismuth-zinc-niobium-oxide (BZN) pyrochlore ceramics are investigated in the wavelength range of 200-1050 nm (200-1500 THz). The Sm content in the Bi1.5-xSmxZn0.92Nb1.5O6.92 solid solution significantly alters the optical properties. Therefore, increasing the Sm doping ratio from x=0.10 to x=0.13 decreased the indirect forbidden energy band gap from 3.60 to 3.05 eV. In addition, above 350 THz, increasing the Sin content decreases the dielectric constant values and alters the dielectric dispersion parameters. The dielectric spectra which were evaluated in the frequency range of 200-1500 THz reflected a sharp decrease in the dielectric constant with increasing frequency clown to 358 THz. The spectra reflected a resonance peak at this frequency. Such resonance spectrum is promising for technological applications as it is close to the illumination of 870 am IR lasers that are used in optical communications. The calculated oscillator (E-o) and dispersion (E-d) energies near that critical range (375-425 THz) reflected an increase in both E-o and E-d with increasing Sm content. (C) 2014 Elsevier B.V. All rights reserved.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.
