Single-ionized-oxygen-vacancy-related dielectric relaxation in Bi3.25La0.75Ti3O12 ferroelectric films

Abstract

The dielectric and conductive properties of Bi3.25La0.75TiO3 ferroelectric films were investigated in the temperature range of 25°C–600°C. A dielectric peak with a relaxation-type characteristic was observed around 400°C. This peak can be greatly suppressed or eliminated by high sintering temperature or annealing in an oxygen atmosphere (O2), and induced again by annealing in a reducing atmosphere (N2). The activation energy of dielectric relaxation and the characteristic relaxation time are estimated to be 1.89eV and 1.08×10−14s, respectively. In the corresponding temperature region, activation energy of conductivity is 0.65eV. The mechanism of this dielectric anomaly is discussed.