Oxygen-vacancy-related dielectric relaxation and conduction mechanisms in Bi5TiNbWO15 ceramics
Oxygen-vacancy-related dielectric relaxation and conduction mechanisms in Bi5TiNbWO15 ceramics作者机构：College of Physics Science and Technology Yangzhou University Yangzhou 225002 China The National Laboratory of Solid State Microstructure Nanjing University Nanjing 210008 China
出 版 物：《Chinese Physics B》 (中国物理B（英文版）)
年 卷 期：2007年第16卷第7期
页 面：2131-2135页
核心收录：
学科分类：07[理学] 070302[理学-分析化学] 0703[理学-化学]
基 金：Project supported by the National Natural Science Foundation of China (Grant No 10274066) and the Natural Science Foundation of Jiangsu Province China (Grant No BK2005052)
主 题：intergrowth dielectric relaxation impedance spectroscopy oxygen vacancies
摘 要：This paper reports that the intergrowth ceramics Bi5TiNbWO15 （BW-BTN） have been prepared with the conventional solid-state reaction method. The dielectric and conductivity properties of samples were studied by using the dielectric relaxation and AC impedance spectroscopy in detail. Two distinct relaxation mechanisms were detected both in the plots of dielectric loss （tanδ） and the imaginary part （Z″） versus frequency in the frequency range of 10 Hz-13 MHz. We attribute the higher frequency relaxation process to the hopping process of the oxygen vacancies inside the grains, while the other seems to be associated with the space charges bound at the grain boundary layers. The AC impedance spectroscopy indicates that the conductivities at 625 K for bulk and grain boundary are about 1.12 × 10^-2 S/m and 1.43 × 10^-3 S/m respectively. The accumulation of the space charges in the grain boundary layers induces a space charge potential of 0.52 eV.
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