La掺杂诱发层状钙钛矿型铁电体弛豫性相变的介电研究

制备了La掺杂层状钙钛矿铁电体材料SrBi₄Ti₄O₁₅, Sr₂Bi₄Ti₅O₁₈以及共生结构Bi₄Ti₃O₁₂-SrBi₄Ti₄O₁₅，通过研究样品的变温介电特性发现，SrBi_4-xLa_{x 关键词： 弛豫性相变 微畴-宏畴 层状钙钛矿 介电性能}

Dielectric study on relaxor-like phase transition of lanthanum doped bismuth layer-structured ferroelectrics

Lanthanum doped bismuth layer-structured ferroelectrics and its intergrowth type, SrBi_4-xLa_xTi₄O₁₅, Sr₂La_xBi_4-xTi₅O₁₈, and (Bi,La)₄Ti₃O₁₂-Sr(Bi,La)₄Ti₄O₁₅, have been prepared by solid-state reaction method. The dielectric properties of those materials are measured. The results show that SrBi_4-xLa_xTi₄O₁₅ (x=1.0), Sr₂La_xBi_4-xTi₅O₁₈(x≥0.5)， (Bi,La)₄Ti₃O₁₂-Sr(Bi,La)₄Ti₄O₁₅(x=1.50) exhibit typical relaxational characteristics. The degree of diffuseness and relaxation increased with increasing La³⁺ content. The origin of relaxation is the microdomain induced by La³⁺ doing. The micromechanism corresponding to the transition between normal ferroelectrics and relaxors is explained as the transition from the macrodomain of normal ferroelectrics to the microdomain of relaxors.