Tl₂LiYCl₆ (TLYC) is an analog to Cs₂LiYCl₆, which is currently an industry‐standard inorganic scintillator for radiation detection with good gamma–neutron discrimination. The presence of thallium (Z = 81) instead of cesium (Z = 55) in the elpasolite structure increases the density of the compound and its stopping power for gamma rays. This work investigates the impact of the Tl atom on the elpasolite structure. Single‐crystal X‐ray diffraction at room temperature and powder neutron diffraction with temperature control were used to characterize the crystal structure of TLYC between 296 and 725 K. The presence of Tl leads to a distortion of the cubic elpasolite structure at room temperature: a tetragonal P4₂ crystal structure (space group 77, a = 10.223, c = 10.338 Å) is identified for TLYC at 296 K. A structural transition to the cubic elpasolite Fm3m phase (space group 225) is observed at 464 K. The thermal expansion of the material for each crystal direction is well described by a linear relationship, except for the region between 400 and 464 K where the lattice parameters converge.

中文翻译：

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锂辉石Tl2LiYCl2的晶体结构和温度依赖性

Tl ₂ LiYCl ₆（TLYC）是Cs ₂ LiYCl ₆的类似物，Cs ₂ LiYCl ₆目前是用于辐射检测的工业标准无机闪烁体，具有良好的伽马-中子分辨能力。th（Z = 81）而不是铯（Z= 55）的锂云母结构增加了化合物的密度及其对伽马射线的阻止能力。这项工作研究了T1原子对锂辉石结构的影响。室温下的单晶X射线衍射和带有温度控制的粉末中子衍射用于表征TLYC在296至725 K之间的晶体结构。Tl的存在导致室温下立方弹性钙钛矿结构的变形：在296 K下对TLYC鉴定出四方P 4 ₂晶体结构（空间群77，a = 10.223，c = 10.338Å）。向立方弹性体Fm 3 m的结构转变 在464 K处观察到相（空间群225）。材料的每个晶体方向的热膨胀通过线性关系很好地描述，除了晶格参数收敛的400和464 K之间的区域。