Phase formation and characterization of high Curie temperature xBiYbO₃-(1 - x)PbTiO₃ piezoelectric ceramics

Novel perovskite xBiYbO₃-(1 - x)PbTiO₃ (BYPT) crystalline solutions were prepared by conventional ceramic processing. The effect of BiYbO₃ on the microstructure and electrical properties was investigated, and the reaction mechanism of phase formation was discussed. The results show that the proper calcining temperature is 860 °C and the optimum sintering temperature is 1140 °C. It is difficult for BYPT ceramics to obtain phase-pure perovskite structures. Pyrochlore phase Yb₂Ti₂O₇ was formed by Yb₂O₃ and TiO₂ that decomposed from BiYbO₃-PbTiO₃ at high temperature. With increasing BiYbO₃ content, the pyrochlore phase Yb₂Ti₂O₇ increases, which resulted in the decrease of densities and piezoelectric constants. The dielectric constants were in the range of 100-700 at room temperature and tan δ less than 4%. BYPT ceramics with high Curie temperatures of >500 °C are obtained. 0.1BiYbO₃-0.9PbTiO₃ ceramic is a very promising material for high-temperature (up to 550 °C) piezoelectric applications for high T_c, stable d₃₃, and high thermal-depoling temperature.