方解石三维热释光特性研究

A study on the three-dimensional thermoluminescence of the calcite crystal

热释光的产生与晶格缺陷有关,而晶格缺陷是由晶格生长过程中的缺损,生长过程中杂质离子的混入,以及核辐射造成完整晶格的损伤等多种方式产生的。因此,天然矿物的热释光性质是矿物晶格缺陷的物性特征之一。本文选择了9个来自不同产地,化学组成略有不同的天然方解石,对其进行了化学组分和经X射线辐照的三维热释光谱测试,并对测试结果进行了分析讨论。结果表明,方解石的热释光发光主要是由Mn2+引起的,发光的强度、峰温的数值与Mn的浓度和猝灭剂(Fe, Co, Ni)的浓度都相关。另外,文中对方解石发光曲线的热释光陷阱深度进行了定量计算,得到其可能存在的陷阱深度分别为1.0~1.1 eV、1.4 eV和1.7 eV。此外,通过对比方解石样品天然热释光和人工X射线辐照产生的热释光发现人工辐照可以使晶体结构中受俘获电子进行重新分布。

Thermoluminescence signals from crystals are closely related to lattice defects which were created in the growth process of crystal. The defects could be produced by the mixing of the impurity ions or the damage of complete crystal lattice by the nuclear irradiation. Therefore, the thermoluminescence property of natural minerals is one of physical properties of crystal lattice defects of minerals. In this paper, nine natural calcite samples from different places were selected for measuring their chemical compositions and three-dimensional thermoluminescence spectra after being irradiated by X rays. Then the obtained measured results for all samples have been analyzed and discussed. The results indicate that the thermoluminescence emission of calcite is mainly resulted from the Mn2+ in lattice of calcite for all the samples. Meanwhile, the emission intensity and peak temperature values of the thermoluminescence signal from calcite are influenced by concentrations of both the luminescence centers(Mn) and quenching centers(Fe, Co, Ni). The possible energy depths of the lattice defects of calcites quantitatively calculated by using the glow curves of thermoluminescence spectra are 1.0~1.1 eV, 1.4 eV, and 1.7 eV, respectively. In addition, the comparison of natural thermoluminesceence and X-ray irradiated thermoluminesceence of calcites has indicated that artificial irradiation could result in the re-distribution of captured electrons in the crystal structures of calcites.