Oxygen-vacancy-related dielectric relaxation and conduction mechanisms in Bi5 TiNbWO15 ceramics
Wang Xiao-Juan(王晓娟)a), Gong Zhi-Qiang(龚志强)a), Qian Ya-Feng(钱亚峰)a), Zhu Jun(朱骏)a), and Chen Xiao-Bing(陈小兵)a)b)†
a College of Physics Science and Technology, Yangzhou University, Yangzhou 225002, China; b The National Laboratory of Solid State Microstructure, Nanjing University, Nanjing 210008, China
Abstract 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 (tan$\delta$) and the imaginary part (Z'') versus frequency in the frequency range of 10 Hz--13MHz. 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 625K for bulk and grain boundary are about 1.12\times10-3S/m and 1.43\times10-3S/m respectively. The accumulation of the space charges in the grain boundary layers induces a space charge potential of 0.52eV.
Received: 16 November 2006
Revised: 14 December 2006
Accepted manuscript online:
Fund: 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).
Cite this article:
Wang Xiao-Juan(王晓娟), Gong Zhi-Qiang(龚志强), Qian Ya-Feng(钱亚峰), Zhu Jun(朱骏), and Chen Xiao-Bing(陈小兵) Oxygen-vacancy-related dielectric relaxation and conduction mechanisms in Bi5 TiNbWO15 ceramics 2007 Chinese Physics 16 2131
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