Influence of grain boundary layers on the dielectric relaxation of Nb-doped SrTiO3

Abstract

The dielectric relaxation of Nb-doped SrTiO3 in the temperature range of 500-900 K was investigated to understand the effect of space charge in grain boundary layers. The dielectric relaxation phenomena were observed for all specimens, regardless of the doping content of Nb. The permittivity maximum temperature (T-epsilon m) shifted and the permittivity peak height varied with the doped content of Nb. In order to study the effect of space charge in the grain boundary on the dielectric relaxation Bi ions were diffused along the grain boundary of a 0.6 mol% Nb-doped SrTiO3 specimen. It was found that the dielectric relaxation behavior changes with the diffusion of Bi. These relaxations can be explained in terms of the space charge which is varied by defects, in grain boundary layers.