Effects of Nb doping on the microstructure, ferroelectric and piezoelectric properties of 0.7BiFeO3–0.3BaTiO3 lead-free ceramics

Abstract

Donor-doped lead-free Bi0.7Ba0.3(Fe0.7Ti0.3)1−x Nb0.66x O3 + 1 mol% MnO2 ceramics were prepared by a conventional oxide-mixed method and the effects of Nb-doping on microstructure, piezoelectric and ferroelectric properties of the ceramics were investigated. All the ceramics exhibit a pure perovskite structure with rhombohedral symmetry. The grain growth of the ceramics is inhibited after the addition of Nb doping. High electric insulation (R = 109–1010 Ω⋅cm) and the poor piezoelectric performance and weak ferroelectricity are observed after the addition of Nb2O5 in the ceramics. Different from the donor effect of Pb-based perovskite ceramics, the introduction of Nb into 0.7BiFeO3–0.3BaTiO3 degrades the piezoelectricity and ferroelectricity of the ceramics. The Bi0.7Ba0.3(Fe0.7Ti0.3)1−x Nb0.66x O3 + 1 mol% MnO2 ceramic with x = 0 exhibits the optimum piezoelectric properties with d 33 = 133 pN C−1 and k p = 0.29 and high Curie temperature (TC = 603∘C).