弛豫铁电体弥散相变的玻璃化特性研究

根据弛豫铁电材料在相变区域的介电弥散行为和玻璃化 液体材料在过冷状态下黏度与温度的行为所共同满足的Vogel-Fulcher 函数关系, 分析了施主替代钛酸钡系列陶瓷的缺陷补偿原理, 通过引入玻璃化液体的构型熵概念, 研究了弛豫铁电材料中钛阳离子缺陷作用势的温度关系, 得到了如下结论: 施主掺杂含量的增加导致了无序度的增加, 钛离子缺陷浓度的增大和平均极性区域尺寸的减小; 在构型熵满足Vogel-Fulcher 函数关系的条件下, 温度越低, 钛离子缺陷作用的范围越大, 极化区域也越大. 缺陷作用的范围随温度的变化导致了弛豫铁电材料的弥散性. 温度下降到一定程度, 冻结效应发生, 介电弥散现象消失.

Study on glassy characteristics of dispersion transition in relaxor ferroelectrics

Based on the common behavior of the Vogel-Fulcher relation followed by both dielectric dispersion of relaxor ferroelectrics in transition region and the viscosity-temperature relation for glassy liquids in supercooled state, vacancy compensation principles of donor doped barium titanate systematic ceramics are analyzed. By the introduction of the concept of configurational entropy, the temperature dependent Ti cation vacancy reaction potential is investigated, and the results show that the increase in donor content gives rise to the increase in disorder degree, the increase in Ti cation vacancy content, and the decrease in size of average polar region; on condition that configurational entropy satisfies the Vogel-Fulcher relation, Ti cation vacancy reaction regime and therefore the polar region will both increase with temperature lowing, and the variation of the regime causes dielectric dispersion of relaxor ferroelectrics. Frozen effect happens and dispersion disappears for the Ti cation vacancy reaction at a certain lower temperature.