Construction of high Tc BiScO3-BiFeO3-PbTiO3 and its enhanced piezoelectric properties by sintering in oxygen atmosphere

Abstract

The high-temperature piezoelectric ceramics 0.36[(1 − x)BiScO3-xBiFeO3]-0.64PbTiO3 was constructed by introducing BiFeO3 with a high Curie temperature (Tc ∼ 830 °C) in the 0.36BiScO3-0.64PbTiO3 binary system. In terms of microstructure, low-melting BiFeO3 plays a role as a sintering aid, lowering the sintering temperature of the ceramic and significantly increasing the grain size. At the same time, the crystal structure shifts from the initial morphotropic phase boundary to the tetragonal phase side, and the Tc increased gradually with increasing BiFeO3 content. Under the conventional air atmosphere sintering conditions, the Tc of the sample with x = 0.3 can reach ∼500 °C, and the piezoelectric constant d33 is 125 pC/N. Compared with that, the d33 of the same composition sample sintered in an oxygen atmosphere is increased to 165 pC/N, which is mainly due to the decrease in the content of oxygen vacancies that helps to increase poling electrical field. Moreover, the oxygen-sintered specimen exhibits an excellent thermal stability in a wide temperature range from room temperature to 450 °C, indicating that it is a promising candidate for ultra-high-temperature piezoelectric devices applications.