Grain-boundary-controlled impedances of electroceramics: Generalized effective-medium approach and brick-layer model.

Autor: Nan, Ce Wen, Zhou, Xisong, Nan, Jun, Wu, Junbo
Předmět:
Zdroj: Journal of Applied Physics; 4/1/2001, Vol. 89 Issue 7, 1 Diagram, 6 Graphs
Abstrakt: In every electroceramic there exist variations throughout the microstructure of both grain size (and shape) and electrical properties of individual grain boundaries. To calculate the effects of such microstructural variations on the frequency-dependent impedance/dielectric behavior, we describe a generalized statistical effective-medium approach based on effective-medium theory. To illustrate the predictions of the approach, the effect of various distributions in the grain boundary conductivity and the grain size, as well as the grain shape and porosity, are considered. The calculations show that such variations lead to depression of the boundary arc and deviations of the impedance spectra from the well-known brick-layer model with an idealized microstructure consisting of identical grains and grain boundaries. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index