钛酸钡基施主掺杂弛豫铁电体介电弥散的唯象分析

弛豫铁电体铁电相变的介电弛豫性涉及外来离子掺杂或原有离子的有序排列, 需要深入理解和有效统一的表征. 针对高浓度施主掺杂在晶粒中产生金属离子缺位, 降低居里温度并引起钛酸钡基铁电材料扩散相变的现象, 分析了高斯型的杂质分布、居里温度分布和金属离子缺位分布的等效对应关系, 得出了在介电常数峰值温区金属离子缺位浓度随温度降低而作用增大的结论, 认为金属离子缺位引起的单极电荷在电场作用下的跳跃运动有可能引起介电弥散和介电损耗. 提出了用‘弛豫度’表征铁电弛豫程度.

Phenomenological analysis for dielectric dispersion of donor doped barium titanate based relaxor ferroelectric

Dielectric dispersion of relaxor ferroelectric in diffusion region is related to the doping of extrinsic ions or ordering arrangement of intrinsic ions. The further explanation and unitive characterization of the dispersion property are required. Focusing on the facts that cation vacancies and dielectric dispersion in barium titanate based relaxor ferroelectric can be caused by donor doping in high concentration, three equivalently correlated Gaussian distributions of doping dopants, Curie temperature, and cation vacancy are obtained. The relevant Gibbs free energy and relation between dielectric constant and temperature of the relaxors with donor doping are deduced. The result demonstrates an increase in concentration of cation vacancy with temperature decreasing in diffusion transition region. The unipole charges caused by the cation vacancies are probably responsible for the dielectric dispersion and loss by their hopping motion.