Microstructure and piezoelectric properties of (Bi0.5Na0.5)1−xBaxTi1−x(Fe0.5Nb0.5)xO3 ceramics

Abstract

In this paper, we report the synthesis, microstructure and some piezoelectric properties of (Bi0.5Na0.5)1−xBaxTi1−x(Fe0.5Nb0.5)xO3 (abbreviated as BNBTFN, x = 0.000, 0.025, 0.050, 0.065, 0.075 and 0.100). The BNBTFN powders were prepared by solid-state reaction method, and their green compacts were sintered at 1150 °C for 2 h. XRD study confirmed that there was no second phase for all the compositions. Morphotropic phase boundary (MPB) of rhombohedral and tetragonal phases existed at x ∼ 0.050, which was close to that of the BNT-BT system. With increasing x, diffuse phase transition, decrease in transition temperature (Tm), and increase in dielectric maximum at the transition temperature (εrm) were observed. The A and B sites simultaneous substitutions, i.e. Ba2+ into (Bi0.5Na0.5)2+ and (Fe0.5Nb0.5)4+ into Ti4+, have some positive effects on piezoelectric properties for x ⩽ 0.05 of (Bi0.5Na0.5)1−xBaxTi1−x(Fe0.5Nb0.5)xO3, despite the lowering of depolarization temperature. Keywords: Lead-free piezoelectric ceramics, Dielectric properties, BNT-BT, Solid-state reaction, Morphotropic phase boundary (MPB)