【摘要】 采用固相合成法制备了La2O3掺杂(Na0.5Bi0.5)0.94Ba0.06TiO3无铅压电陶瓷。研究了La2O3掺杂对(Na1/2Bi1/2)TiO3陶瓷晶体结构、介电性能与介电弛豫行为的影响。XRD分析表明,在所研究的组成范围内陶瓷材料均能够形成纯钙钛矿固溶体。材料的介电常数-温度曲线显示陶瓷具有两个介电反常峰Tf和Tm。修正的居里-维斯公式较好的描述了陶瓷弥散相变特征,弥散指数随La2O3掺杂量的增加而增加。掺杂量较低的陶瓷仅在低温介电反常峰Tf附近表现出明显的频率依赖性,随掺杂量的增加,陶瓷材料在室温和低温介电反常峰Tf之间都表现出明显的频率依赖性。并根据宏畴-微畴转变理论探讨了该体系陶瓷介电弛豫特性的机理。更多还原

【Abstract】 The dielectric properties and relaxation of La2O3 doped (Na0.5Bi0.5)0.94Ba0.06TiO3 lead-free piezoelectric ceramics were investigated. X-ray diffraction showed that La ions diffused into the lattice of (Na0.5Bi0.5)0.94Ba0.06TiO3 to form a solid solution with perovskite-type structure. The temperature dependence of dielectric constant εr revealed that the solid solution exist two dielectric abnormal peaks Tf and Tm. The thermal variation of the permittivity was well described by a law 1/ε-1/εm=C(T-Tm)α and the diffuse coefficient α value increased with increasing concentration of La2O3. All samples exhibited relaxor characteristics different from classic relaxor ferroelectrics. The samples with a low doping level of La2O3 exhibited obvious frequency dependent only near Tf and the samples with a high doping level of La2O3 exhibited obvious frequency dependence between room temperature and Tf. The mechanism of relaxor behavior was also discussed according to the macro-domain to micro-domain transition theory.更多还原