Enhancement in multiferroic and piezoelectric properties of BiFeO3-BaTiO3-Bi0.5Na0.5TiO3 lead-free ceramics with MnO2 addition by optimizing sintering temperature and dwell time

摘要

Multiferroic ceramics of 0.705BiFeO3-0.275BaTiO3-0.02Bi0.5Na0.5TiO3 + 1 mol% MnO2 were prepared by a conventional ceramic technique and the effects of sintering temperature (Ts) and dwell time (ts) on the phase structure, piezoelectric and multiferroic properties of the ceramics were investigated. As Ts increases from 880 °C to 1040 °C, the ceramics are transformed from rhombohedral to tetragonal structure and a MPB is formed at Ts = 1000 °C and ts = 2 h. The increase in Ts greatly improves the densification, electric insulation, ferroelectricity and piezoelectricity of the ceramics, while relatively weak dependences on ts are observed. As Ts increases from 880 °C to 1000 °C, the magnetism of the ceramics is significantly enhanced and the values of Mr are increased by ∼400%. The optimum sintering conditions of the ceramic is 1000 °C/2 h, in which high density, good electric insulation and enhanced ferroelectricity (Pr = 18.4 μC/cm2), piezoelectricity (d33 = 140 pC/N, kp = 31.4%) and ferromagnetism (Mr = 0.099 emu/g) are simultaneously obtained.