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Article Citation - WoS: 17Citation - Scopus: 19Synthesis and Characterization of Bi1.5zn0.92< Pyrochlore Ceramics(Elsevier Sci Ltd, 2012) Qasrawi, A. F.; Kmail, Bayan H.; Mergen, A.The morphological, compositional, structural, dielectric and electrical properties of Bi1.5Zn0.92Nb1.5-xSnxO6.92-x/2 ceramics have been investigated by means of scanning electron microscopy (SEM), X-ray energy dispersion spectroscopy (EDS), X-ray diffraction (XRD), temperature and frequency dependent dielectric constant and temperature dependent conductivity measurements for Sn-contents in the range of 0.00 <= x <= 0.60. It was shown that single phase of the pyrochlore ceramics can only be obtained for x <= 0.25. Above this value a ZnO phase appeared in the XRD patterns and SEM micrographs as well. An increase in the lattice constant and in the temperature coefficient of dielectric constant and a decrease in the dielectric constant values with increasing Sn content was observed for the ceramics which exhibited a single phase formation. A temperature dependent but frequency invariant dielectric constant was observed for this type of ceramics. The lowest electrical conductivity and highest dielectric constant was observed for the sample which contains 0.06 Sn. The Bi1.5Zn0.92Nb1.5-xSnxO6.92-x/2 pyrochlore ceramic conductivities are thermally active above 395 K. For temperatures greater than 395 K, the conductivity activation energy which was found to be 0.415 eV for the pure sample increased to 1.371 eV when sample was doped with 0.06 Sn. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.Article Citation - WoS: 8Citation - Scopus: 10Structural, Electrical and Dielectric Properties of Bi1.5zn0.92< Pyrochlore Ceramics(Elsevier Sci Ltd, 2012) Qasrawi, A. F.; Mergen, A.The micro-structural, compositional, temperature dependent dielectric and electrical properties of the Bi1.5Zn0.92Nb1.5-xTaxO6.92 solid solution has been investigated. The increasing Ta content from 0.2 to 1.5 caused; single phase formation, a pronounced grain size reduction from similar to 7.0 to 2.5 mu m, sharp decrease in the dielectric constant from 198 to 88 and an increase in the electrical conductivity from 3.16 x 10(-10) to 5.0 x 10(-9) (Omega cm)(-1), respectively. The temperature dependent dielectric constant which is found to be frequency invariant in the frequency range of (0.0-2.0 MHz) exhibited a sharp change in the temperature coefficient of dielectric constant at a (doping independent) critical temperature of 395 K. The analysis of the measured data reflects a promising future for this type of pyrochlore to be used in high voltage passive device applications. (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.Article Citation - WoS: 77Citation - Scopus: 78Electrical Properties of Al/Pcbm:zno Heterojunction for Photodiode Application(Elsevier Science Sa, 2020) Gullu, H. H.; Yildiz, D. E.; Kocyigit, A.; Yildirim, M.In this paper, the electrical characteristics of spin-coated PCBM:ZnO interlayered Al/PCBM:ZnO/Si diode are investigated under the aim of photodiode application. Under dark condition, the diode shows about four orders in magnitude rectification rate and diode illumination results in efficient rectification with increase in intensity. The analysis of current-voltage curve results a non-ideal diode characteristics according to the thermionic emission model due to the existence of parasitic resistances and interface states. The measured current-voltage values are used to extract the barrier height and ideality factor under dark and illumination conditions. Under illumination, photo-generated carriers contribute to the current flow and linear photo-conductivity behavior in photo-current measurements with illumination shows the possible use of hybrid PCBM:ZnO layer in Si-based photodiodes. In addition, change in the series and shunt resistance values under illumination is found to be effective in this light-sensing behavior of the diode. This characteristic is also observed from the typical on/off illumination switching behavior for the photodiodes in transient photo-current, photo-capacitance and photo-conductance measurements with the quick response to the illumination. The deviations from ideality are also discussed by means of distribution of interface states and series resistance depending on the applied frequency and bias voltage. (C) 2020 Elsevier B.V. All rights reserved.
