The effect of post-sintering annealing upon the dielectric relaxation behavior was studied in (Sr1-1.5xLax)TiO3 at temperatures ranging from 1.5 to 300K. The results showed that dielectric permittivity peaks with frequency dispersion could be gradually and completely eliminated by annealing in an oxidizing atmosphere, and could be recovered by annealing in a reducing atmosphere. It was concluded that these anomalies were closely related to O vacancies.

Oxygen-Vacancy Related Dielectric Anomalies in La:SrTiO3. Z.Yu, C.Ang, L.E.Cross: Applied Physics Letters, 1999, 74[20], 3044-6