Brick layer model analysis of nanoscale-to-microscale cerium dioxide

被引:96
作者
Hwang, JH [1 ]
McLachlan, DS
Mason, TO
机构
[1] Northwestern Univ, Dept Mat Sci & Engn, Evanston, IL 60208 USA
[2] Univ Witwatersrand, Dept Phys, ZA-2050 Wits, South Africa
关键词
nanocrystals; cerium oxide; grain boundaries; dielectric constant; brick layer model;
D O I
10.1023/A:1009998114205
中图分类号
TQ174 [陶瓷工业]; TB3 [工程材料学];
学科分类号
0805 ; 080502 ;
摘要
The frequency-dependent impedance/dielectric behavior of the brick-layer model (BLM) was investigated vs. grain size and local parameters (resistivity, dielectric constant, and grain boundary width). The simulation shows a maximum in capacitance vs. grain size, governed by the grain boundary-to-grain interior resistivity ratio. The BLM was employed to analyze the 500 degrees C impedance behavior of polycrystalline cerium dioxide from the nano- (similar to 15 nm grain size) to the micro- (similar to 4 mu m grain size) regime. The grain boundary resistivity is orders of magnitude larger than that of the grain interiors in the microcystalline specimen. This contrast is significantly smaller in the nanocrystalline specimens, suggesting enhanced conduction at grain boundaries. The limitations of the BLM for simulating the behavior of complex electroceramic microstructures are discussed.
引用
收藏
页码:7 / 16
页数:10
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