Impedance relaxation of at high temperatures

Abstract

Measurements of complex ac impedance of have been carried out. The dielectric constant showed a high-temperature anomaly around for the c axis and for the a axis). An equivalent circuit model based on two parallel G - C circuits was adopted to describe the impedance relaxational behaviour observed below and above . From this method we could estimate the relaxation times consisting of two components: the fast component due to proton migration and the slow component resulting from electrode - crystal interfacial polarization. The slow component relaxation time tends to increase markedly on crossing , the possible origin of which is considered to be the partial decomposition of crystal on the surface of crystal.