Microstructure, dielectric and ferroelectric properties of (1-x)(0.94Bi_(0.5)Na_(0.5)TiO_3–0.06BaTiO_3)–xBiFeO_3 lead-free ceramics synthesized via a high energy ball milling method

摘要

(1-x)[0.94Bi_(0.5)Na_(0.5)TiO_3–0.06BaTiO_3]–xBiFeO_3 lead-free ceramics (BNBT–xBFO, x = 0, 0.01, 0.03 and 0.07) with fine grain sizes were prepared by solid state reaction of high energy ball milled (HEBM) powders. Xray diffraction (XRD) patterns exhibited single perovskite structure for the BNBT–xBFO ceramics sintered at an optimum temperature of 1170 ℃. Quantitative analysis of the XRD patterns showed that relative amount of tetragonal phase decreased with increasing content of BFO. Due to the effects of HEBM, average grain size of the BNBT–xBFO ceramics was smaller than 1.46μm and varied with content of BFO. Two dielectric anomalies were observed in ε_r -T curves. The degree of diffuseness of the phase transition around T_m became more evident with increasing content of BFO. The variation in polarization with BFO amount is consistent with that in mean grain size with BFO amount.