dc Electrical Degradation of Perovskite‐Type Titanates: I, Ceramics

Abstract

The rate of the resistance degradation of doped SrTiO 3 ceramics is investigated as a function of various external and material parameters. The effects of the mutually interrelated parameters dc voltage, dc electric field, and thickness of the dielectric are described by power laws. Electron microscopic potential contrast studies show a Maxwell‐Wagner polarization leading to a concentration of the electric field at the grain boundaries during the degradation. Based on this finding, the voltage step per grain boundary, ΔΘ gb , is introduced as a rate‐determining parameter which allows an explanation of the influence of the grain size on the degradation rate as well as the difference in the power laws for ceramic and single‐crystal samples.