Change in cation nonstoichiometry at interfaces during crystal growth in polycrystalline BaTiO3

Abstract

Using an embedded single crystal in a polycrystalline matrix and quantitative electron energy loss spectroscopy, we have demonstrated that Ti-excess grain boundary nonstoichiometry can vary with the extent of boundary migration. While a slight excess in Ti was detected at the boundaries between small matrix grains, a large increase in Ti/Ba ratio, to as much as similar to 1.50 compared to the stoichiometric value, was present at the interface between a growing single crystal and the matrix grains when the embedded crystal grew up to a few hundred micrometers. This change in nonstoichiometry was attributed to a continuous accumulation of excessive Ti at the moving boundary during crystal growth. The present result indicates that growth kinetics can critically affect the interface chemistry in polycrystals. (c) 2006 American Institute of Physics.