Impedance spectroscopy of acceptor-doped CaZrO3 with cation nonstoichiometry

Abstract

The electrical conductivities of acceptor-doped Ca1-x Zr0.99M0.01O3-delta (M = Mg2+, In3+) systems have been investigated as a function of cation nonstoichiometry (0 <= x <= 0.05). The electrical characterization was carried out using impedance spectroscopy at different temperatures in dry air. The contributions of grain (R-g) and grain boundary resistance (R-gb) to the total resistance (R-t) were examined with the impedance and/or modulus plane representation. For the stoichiometric composition, the R-t of the specimen decreased with acceptor doping. When Ca deficiency was small, both the R-g and the R (gb) slightly increased with nonstoichiometry (x). However, when Ca deficiency was large and excess zirconia was found as a second phase, the R-gb and the contribution of the R-gb to the R-t significantly increased with x.