The impedance analysis for the aging mechanism of CaO excess type calcium zirconate electrolyte material comparing with 8.5 YSZ

•Confirmed the aging behavior in CaO excess calcium zirconate perovskite ceramics•The aging behavior works more seriously as temperature rises.•The Ca1.1Zr0.9O2.9 presents a much more stable conductivity than the 8.5 YSZ shows.•The annealing operation enforces the formation of association [CaZr″ − VO••] and makes oxygen vacancy trapped.•The lock of oxygen vacancy reduces its effective diffusion coefficient.

A CaO excess type calcium zirconate electrolyte with a composition of Ca1.1Zr0.9O2.9 was prepared. Its aging behavior at 900 °C and 1100 °C was evaluated by AC impedance. The conductivity decreases more seriously at higher temperature. Combined with the aging effect of 8.5 YSZ, the formation of [CaZr″ − VO••] promoted by annealing operation should be responsible for the aging effect in Ca1.1Zr0.9O2.9. The declined mobility of VO•• is viewed as the increase in hopping activation energy and the decrease in effective concentration of VO••. Consequently, the diffusion coefficient of VO•• decreases and results in the aging behavior.