Grain-boundary plane orientation dependence of electrical barriers at Sigma 5 boundaries in SrTiO3

Abstract

Dependence of the electrical properties on grain-boundary plane orientation is examined by a combination of high-resolution transmission electron microscopy, impedance spectroscopy, and electron energy-loss spectrometry using two kinds of SrTiO3 Sigma 5 ([100]/36.8 degrees) bicrystalline grain boundaries: symmetric (310) (18.4 degrees/18.4 degrees) and asymmetric (8.4 degrees/28.4 degrees). While the symmetric grain boundary is observed to be straight with the symmetric (310)//(310) plane orientation, the asymmetric grain boundary is faceted into symmetric (310)//(310) and (210)//(210), and asymmetric (100)//(430). Grain-boundary impedance is observed only in the asymmetric grain boundary, and the electron energy-loss spectrometry quantification indicates that the asymmetric (100)//(430) facets are more oxygen-deficient than the symmetric ones. The results suggest that the asymmetric (100)//(430) facets are the most resistive among the three different facets. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.