Modification of both Pr and Td in ZnO-doped 0.97(Bi0.5Na0.5)TiO3-0.03BiAlO3 ferroelectric ceramics

Abstract

Bi0.5Na0.5TiO3(BNT)-based ferroelectric ceramics demonstrate significant potential for application in high-power ferroelectric generators. However, their practical utilization is hindered by poor thermal stability resulting from a low depolarization temperature (Td). In this work, we simultaneously improve the remnant polarization (Pr) and Td of 0.97BNT-0.03BiAlO3 ceramics via moderate ZnO doping. The effects of ZnO doping on the sintering temperature, ferroelectricity and depolarization behavior of 0.97BNT-0.03BiAlO3 ceramics are systematically studied. The optimum sintering temperature of 0.97BNT-0.03BiAlO3 ceramics decreases from 1140 °C to 1000 °C by approximately 140 °C and the density becomes higher after ZnO doping. At x = 0.01, the phase structure remains R3c rhombohedral phase, and Zn2+ diffuses into the crystal lattices. However, when x ≥ 0.02, the secondary phases ZnO and ZnAl2O4 appear. As the ZnO content increases from x = 0 to x = 0.04, the Pr value shows a continuous increase from 31.13 µC/cm2 to 39.84 µC/cm2, while the Td value initially rises by 32 °C from 156 °C to 188 °C and then decreases to 163 °C. Notably, the highest Td is achieved at x = 0.02, owing to the combined effects of Zn2+ substitution and localized stress between the matrix and the composite. These findings highlight doping ZnO as an effective approach to optimize both Td and Pr of BNT-based materials.