Improved ferroelectric properties of BiFeO3-based piezoelectric ceramics through morphotropic phase boundary construction

The ceramic (1-x)BiFe0.985Sc0.015O3-xBaZr(0.2)Ti(0.8)O(3) + 1mol% MnO2 (x = 0.20, 0.25, 0.30, 0.35) (BFS-xBZT) was synthesized using the traditional ceramic sintering method. The components of the ceramic were determined by constructing a morphotropic phase boundary (MPB) which consists of rhombohedral (R) and tetragonal (T) phases (0.24 <= x <= 0.26). With the accumulation of BZT content, relax behaviors were observed by dielectric properties measurements. At the MPB, the crystal structures of the R phase and T phase change abruptly. The distortion degree of the R phase increases, and the differences between a and c of the T phase decrease. An enhanced ferroelectricity Pr of similar to 27.8 mu C/cm(2) and apex piezoelectric coefficient d(33) of 131 +/- 4 pC/N are obtained near the MPB (x = 0.25), due to the R-T phase coexistence near room temperature. The results show that BFS-xBZT ceramics could be a candidate for lead-free piezoelectric ceramics at high operating temperatures.