【摘要】 测量了不同掺杂改性的 PbZrO₃-PbTiO₃和 PbTiO₃系压电陶瓷的正电子寿命谱。按照正电子捕获理论对实验所得寿命谱参数与陶瓷微观结构缺陷的关系作了讨论。结果表明,长寿命成分τ₂（约300ps）相当于PZT或PT陶瓷中Pb空位缺陷对正电子的捕获。由缺陷对正电子的捕获率x随 PT中掺La³⁺量增加而增大的现象,证实了La³⁺占据ABO₃钙钛矿结构中的A位并产生Pb空位,而正电子可作为探测这种Pb空位浓度的一种手段。由PZT中x值与掺Bi³⁺量的关系来推断,当 Bi³⁺离子在较少掺杂量下主要进入A位,而在较大掺杂量下开始占据B 位产生氧空位。实验表明,正电子湮没技术是一种研究掺杂改性陶瓷微观结构缺陷变化的有力手段。更多还原

【Abstract】 Positron lifetime spectra in differently doped and modified piezoelectric ceramics ofPbZrO₃-PbTiO₃ and PbTiO₃ systems were measured.Relationship between parameters ofpositron lifetime spectra and the microstructure defects of ceramics was discussed basedon the positron trapping theory.The results suggest that the long lifetime component τ₂（about 300 ps ） corresponds to the positron trapping in the Pb cation vacancies in PZT orPT ceramics.The fact that the positron trapping rate x increases with doped La³⁺ in PTceramics suggests that La³⁺ does occupy the A sites in ABO₃ perovskite structure andcreate Pb vacancies, and positron can be used as a measure in detecting such Pb cationvacancies.It is inferred from the relationship between x and doped amount of Bi³⁺ inPZT system that Bi³⁺ ions enter A sites essentially when the doped amount ot Bi³⁺ issmall, while Bi³⁺ ions begin to occupy the B sites and create oxygen vacancies when thedoped amount of Bi^a+ is large.It is clear from the experiments that the positron annihila-tion technique is an effective tool for studying defects in doped ceramics.更多还原