热释光缺陷模型的探讨

Exploring the defect model in thermoluminescence

热释光物理机制的描述及相关理论模型的建立依赖于所采用的缺陷模型。热释光动力学模型基于固体能带理论和孤立点缺陷的假设,完全不涉及介质中的缺陷结构和空间分布。实际应用中,动力学模型参数并不能给出确切的意义,对许多热释光物理现象也无法解释。本文基于掺入稀土的碱土硫酸盐磷光体的系统实验研究,分析了热释光三维发光谱和剂量响应非线性特性,结果显示,大多数热释光磷光体中缺陷是以缺陷复合体的形式存在,本征缺陷和掺入杂质构成的缺陷复合体是热释光多阶段随机过程的基本作用单元,表明热释光磷光体的发光特性和剂量响应非线性特性与缺陷复合体的结构密切相关。

The accuracy to describe thermoluminescence（TL） mechanism depends on the defect models used principally. The TL kinetic theory models are based on the isolated point defects hypothesis. In fact, the kinetic parameters obtained from experimental TL glow curves have little physical significance. It is known that a lot of TL physical phenomena cannot be explained by the TL kinetic theory models. Based on analysis of TL emission spectra and nonlinearity of TL dose responses in the series of alkaline earth sulphate doped with rare earth ions and phosphors, it is supposed that the defects in these phosphors should be formations of large defect complexes, which include intrinsic imperfects and dopants. These defect complexes can be regarded as basic elements in the TL multi-stage processes. It has been observed that the TL characteristics and the nonlinearity of dose responses depend on the structure of these defect complexes obviously.