Enhanced piezoelectric properties and electric thermal stability of high temperature BiFeO3-PbTiO3-BaTiO3 piezoelectric ceramics with Bi2O3 excess

BiFeO
₃
-PbTiO
₃
-BaTiO
₃
ceramics are one of promising candidates for high temperature piezoelectric applications. High piezoelectric properties are important factors for real device applications. In this paper, 0.62BiFeO
₃
-0.23PbTiO
₃
-0.15BaTiO
₃
-1 mol%MnO
₂
+x mol%Bi
₂
O
₃
(x = 0, 1, 3 and 5) (BF-PT-BT) ceramics near the morphotropic phase boundary (MPB) compositions with both rhombohedral (R) and tetragonal (T) phases were prepared by the conventional solid-state reaction method, and effects of Bi excess on the electric properties were studied. X-ray diffraction (XRD) reveals that the R phase decrease and the tetragonal distortion is enlarged from 1.051 to 1.073 with the increase of Bi
₂
O
₃
content. SEM images reflect that the BF-PT-BT ceramics are denser and the grain sizes are enlarged significantly with the addition of appropriate amount of excessive Bi. The piezoelectric coefficient is enhanced, while the dielectric loss is decreased obviously. Furthermore, the enhance electric properties may result from the increased relative density and suitable grain size. These results indicate that moderate excess Bi
₂
O
₃
addition is an effect way to tailor the electric properties in BF-PT-BT solid solutions. The optimal properties of BF-PT-BT ceramics appear at 1mol% excessive Bi, with typical values of Curie temperature T
_c
, dielectric constant εr (1 kHz), dielectric loss tanδ (1 kHz), piezoelectric coefficient d
₃₃
, depolarization temperature T
_d
are 546 °C, 558, 0.008, 222 pC/N, 500 °C, respectively.