Resistance degradation behavior of Ca-doped BaTiO₃

Resistance degradation of Ca-doped BaTiO₃ceramics was investigated. A series of coarse and fine-grained (Ba_1–xCa_x)TiO₃with only Ba site incorporation rangingxfrom 0 to 0.1, and Ba(Ti_1–yCa_y)O₃ceramics with only Ti site incorporation rangingyfrom 0 to 0.015, were prepared with similar grain sizes. The increase ofxdid not cause any distinct difference in degradation, whereas an increase inycaused a significant resistance degradation in both coarse and fine-grained specimens. The variation of ionic transference number (t_ion) as evaluated by the Warburg impedance was negligible with increase inx, but significantly increased with the increase iny. These results demonstrate that the decrease of lattice parameters and lattice shrinkage by the Ba site incorporation of Ca has little influence on the resistance degradation, and that the oxygen vacancy concentration generated by the Ti site incorporation of acceptor Ca is a very important factor that governs resistance degradation.