Morphotropic phase boundary and electrical properties in (1-x) Bi₀.₅Na₀.₅TiO₃-xBi(Zn₀.₅Ti₀.₅)O₃lead-free piezoceramics

Abstract

(1−x)Bi₀.₅Na₀.₅TiO₃-xBi(Zn₀.₅Ti₀.₅)O₃[(1−x)BNT−xBZT, x=0, 0.025, 0.0375, 0.050, and 0.075] lead-free piezoceramics were prepared and their structures and electrical properties were investigated. It is found that BZT can increase the Curie temperature of BNT. A morphotropic phase boundary (MPB) separating rhombohedral and tetragonal phases exists near x=0.0375. As the result, the MPB composition shows improved electrical properties; the saturated polarization, remnant polarization, and coercive field are 42.0 μC/cm², 36.5 μC/cm², and 3.5 kV/mm, respectively, while the piezoelectric coefficient, planar electromechanical coupling factor, and unipolar strain are 92 pC/N, 0.22, and 0.08%, respectively. The structures and electrical properties are discussed by comparing with that of other BNT-based piezoceramics. Our results do not only supplement for BNT-based lead-free piezoceramics, but also may provide a way to develop new lead-free piezoceramics with high Curie temperature.