Reduced dielectric loss and improved electric thermal stability of BF–PT–BT ceramics by Mn additions

Obtaining piezoelectric ceramics with large piezoelectric coefficient, good electric thermal stability and low dielectric loss remain a harsh task. In this work, 0.62BiFeO 3 –0.23PbTiO 3 –0.15BaTiO 3 -xmol%MnO 2 (BF–PT–BTMn) ceramics were prepared by high-temperature sintering method, and effects of Mn contents on the structure, dielectric and piezoelectric properties were studied. BF–PT–BTMn ceramics show dominant perovskite structure with the coexistence of rhombohedral and tetragonal phases, and volume fraction of rhombohedral phase increases monotonously with the Mn content. The room temperature dielectric loss of BF–PT–BTMn ceramics is reduced from 0.05 down to 0.008, while the piezoelectric coefficient is improved from 163 pC/N up to 238 pC/N at MnO 2 content of 0.8 mol%. Their Curie temperatures of BF–PT–BTMn ceramics are about 546 °C, which is not sensitive to the MnO 2 content. The maximum piezoelectric coefficient of BF–PT–BTMn ceramics is at least 100 pC/N higher than that of BF-based piezoelectric ceramics with Curie temperature above 500 °C reported in the literature. Noted that the high-temperature resistivity (400 °C) and depoling temperature of BFPTBT-0.8 mol% MnO 2 are 8 and 1.6 times those of the ceramics without MnO 2 additions, respectively. Furthermore, the variation of the piezoelectric coefficient for BF-PT-BT-0.8 mol%MnO 2 is only about ± 5% during the room temperature to 500 °C, showing good piezoelectric thermal stability. These results showed that the BF–PT–BTMn ceramics were competitive candidates for high-temperature piezoelectric applications.