Electrical properties and thermal stability of Ce-modified Ca0.80(Li0.5Bi0.5)0.20Bi2Nb2O9 ceramics

Ce-modified Ca0.80(Li0.5Bi0.5)0.20Bi2Nb2O9 ceramics (Ca0.80(Li0.5CexBi0.5-x)0.20Bi2Nb2O9) were synthesized by conventional solid state sintering method. The effects of Ce additives on the electrical properties were studied. With the increase of Ce content, the piezoelectricity of the ceramics was significantly enhanced, and the Curie temperature (TC) decreased from 941 °C to 917 °C, leading to the relatively poor thermal stability in the ceramics. The Ca0.80(Li0.5Ce0.15Bi0.35)0.20Bi2Nb2O9 (CBNLB-C15) ceramics possessed the optimum properties, and the d33 value was found to be ∼17.2 pC/N, together with a high TC (∼928 °C). In addition, a good performance of thermal stability that remained 89.5% of its d33 (∼15.4 pC/N) was obtained when annealing temperature was 900 °C. The detailed electrical properties of samples in high temperature region were determined by using electrochemical impedance spectra. The results revealed that the degradation of resistance may be attributed to the substitution of Nb5+ ions by Ce4+ ions, and oxygen vacancies make a major contribution to electrical conduction.