Structure and electrical properties of ternary BiFeO₃-BaTiO₃-PbTiO₃ high-temperature piezoceramics

In the current work, the bulk ternary (0.85-x) BiFeO₃-xBaTiO₃-0.15PbTiO₃ (BF-BTx-PT, x=0.08-0.35) system has been studied as a potential high-temperature piezoceramics. Samples with various content of BT were prepared via solid-state route, and pure perovskite phase was confirmed by X-ray diffraction. The temperature dependence of dielectric constants confirmed the decrease of Curie temperature with increasing BT content. It was found that the morphotropic phase boundary (MPB) composition of BF-BTx-PT ceramics was in the vicinity of x=0.15, which exhibits optimal properties with piezoelectric constant d₃₃ of 60 pC/N, high Curie temperature of 550 ℃, and low sintering temperature of 920 ℃. Measurements also showed that the depoling temperature was 300 ℃, about 150 ℃ higher than that of commercialized PZT ceramics, which indicated good temperature stability. BF-BTx-PT ceramics are promising candidates for high temperature applications.