Large piezoelectric responses of Bi(Fe,Mg,Ti)O3-BaTiO3 lead-free piezoceramics near the morphotropic phase boundary

The (1- x )Bi 1+ y (Fe 0.96 Mg 0.02 Ti 0.02 )O 3 - x BaTiO 3 (abbreviated as B 1+ y FMT- x BT) system was designed to explore the morphotropic phase boundary (MPB) separating rhombohedral ( R ) and tetragonal ( T ) phases, and the mechanism of performance enhancement. The phase structure of samples was discreetly investigated by X-ray diffraction, and Rietveld refinement results of the XRD data revealed that the B 1+ y FMT- x BT ceramics consist of an R phase at x  = 0.24, two R and T phases at 0.26 ≤  x  ≤ 0.32, and a single T phase at x  = 0.34. Because of the MPB and the improvement of resistivity with adding excess Bi compensation, excellent piezoelectric properties of d 33  = 198 pC/N and k p  = 30.9%, as well as high Curie temperature T C  = 497 °C were achieved in the B 1+ y FMT- x BT system at x  = 0.30 and y  = 0.02. Here, the large d 33  = 198 pC/N which is the maximum value for the BF-BT-Bi(Mg,Ti)O 3 system so far, and high T C  = 497 °C suggest that Bi(Fe,Mg,Ti)O 3 -BaTiO 3 ceramics have good prospects in high-temperature piezoelectric devices.