放电等离子烧结铁酸铋陶瓷的组织与性能

Microstructure and Properties of BiFeO_3 Ceramics by Spark Plasma Sintering

采用改进的固相烧结法制得不同粒径(0.1μm-10μm)的铁酸铋(B iFeO3)单相粉末,将混杂工艺应用于放电等离子烧结技术(SPS)中进行B iFeO3单相粉末的二次烧结,制备得到高质量多铁性陶瓷材料,并对其介电性能进行了测试。研究结果表明,与传统的制备方法相比,该方法的烧结温度低,制得的B iFeO3陶瓷具有具有较好的组织和结构,在650℃烧结时相对密度达到97.3%,压电系数d33为13.6 pC/N。经过氧气退火处理后的陶瓷具有明显的介电频率弥散及高温与低温两个阶段的介电弛豫行为。样品通过真空条件下退火后,由于铁离子价态的波动被抑制,低温介电弛豫现象消失。

Single phase multiferroic BiFeO3 powder was prepared by improved solid state synthesis,and dense BiFeO3 ceramics were fabricated by spark plasma sintering（SPS） process.The particle size of BiFeO3 powder used for second sintering by SPS ranging from 0.1 m to 10 m.It is found that the sample has not only single phase but also high density of 97.3% when sintered at 650℃.The piezoelectric coefficient d33 of the sample is 13.6 pC/N at room temperature.Oxygen and vacuum annealing conditions impact dielectric behavior of BiFeO3 ceramics prepared by SPS technique obviously.Two kinds of dielectric relaxation following the Arrhenius law were detected in low and high temperature ranges,respectively.The low temperature dielectric relaxation could be almost completely removed by annealing in vacuum and it should be assigned to be a valence fluctuation of Fe ions,while the high temperature dielectric relaxation was proposed to stem from the short range motion of oxygen vacancies.