POLARONIC RELAXATION IN PEROVSKITES

We report a low-temperature loss anomaly in several oxidic perovskites such as KTaO3, KTaO3:Nb, SrTiO3, SrTiO3:Ca, PbTiO3:La, Cu, and BaTiO3 :La. We show that this anomaly arises from a low-frequency dielectric relaxation. The activation energy and the relaxation time of this proc ess are nearly the same for all the investigated perovskites disregard ing their composition, texture, and ferroelectric properties. We thus ascribe the loss anomaly to the localization of polarons on residual d efects. Although the dielectric losses in SrTiO3 and SrTiO3:Ca are qua litatively similar to other perovskites, the loss anomaly occurs at mu ch lower temperatures: 10 instead of 40 K.