钨酸铅晶体中的偶极缺陷

在用阻抗谱研究PbWO₄（PWO）晶体的介电特性时发现，掺La³⁺的PW O晶体中存在典型的介电弛豫现象，它被归因于La³⁺进入Pb位并与铅空位V_Pb缔合 成偶极缺陷.这一结果不仅清楚地证明了PWO晶体中铅空位的存在，而且表明阻抗谱测试可以成为PWO晶体微结构研究的有力工具.以阻抗谱测试为主要工具，结合光吸收谱（包括红外谱）和x射线光电子能谱，阐明了在异价掺杂离子（3+，4+，5+以及3+和5+双掺）掺杂的PWO晶体中 关键词： 钨酸铅 偶极缺陷 异价掺杂 退火效应

Dipolar defect complexes in single-crystal PbWO4

We have previously demonstrated the presence of the defects complex ［2(La^{3 +} _Pb)^·-V″_Pb］in La-doped lead tungs tate (PWO). That earl ier experimental technique was supplemented with x-ray photoelectron, visible ab sorption and infrared absorption spectroscopies in the present investigation on PWO crystals doped with 3+, 4+ or 5+ cations, or co-doped with 3+ and 5+ impurit ies. Useful information has been deduced on dopant lattice sites, dipolar defect s complexes, their relation with materials properties, and their transformation during annealing. Some of the deductions have also been corroborated with comput er simulation. The present work argues against the conception that impedance spe ctroscopy cannot provide definite conclusions on defect structures in ionic soli ds.