Impedance behavior of excess CaO type non-stoichiometric Ca1−xZrO3−δ perovskite ceramic

Excess CaO type non-stoichiometric Ca1−xZrO3−δ (x = −0.2, −0.23) was prepared to investigate their impedance behavior in 500 °C–1100 °C temperature range. It was confirmed that grain plays predominantly role in total resistance and relaxation process. The grain boundary resistance decreases more rapidly than that of grain with the rising of temperature. The relaxation time was found reduces with temperature increases. The activation energies are calculated to be 1.19 eV of C1.2Z and 1.53 eV of C1.23Z. The excess CaO is suggested can enhance the resistance and relaxation process of grain boundary and gives rise to a higher activation energy of C1.23Z. By analyzing dielectric permittivity, polarization effect was verified works more seriously at higher temperatures especially in C1.2Z. The excess CaO was proved can relieve the polarization effect in C1.23Z.

► We prepared CaO excess Ca1−xZrO3−δ perovskite ceramics and investigated their impedance behavior.
► The resistance and relaxation process in Ca1−xZrO3−δ are predominantly affected by grain.
► The excess CaO can enhance the resistance and relaxation process of grain boundary part.
► The polarization effect works more seriously in the Ca1−xZrO3−δ with single phase especially in higher temperature.
► The excess CaO hinders the transfer of charge carriers but relieves the polarization effect.