The structure of calcium europium orthoborate, Ca₃Eu₂(BO₃)₄, was determined using high‐resolution powder X‐ray diffraction data collected at the ID22 beamline (ESRF) under ambient conditions, as well as at high temperature. Rietveld refinement allowed determination of the lattice constants and structural details, including the Ca/Eu ratios at the three cationic sites and their evolution with temperature. Clear thermal expansion anisotropy was found, and slope changes of lattice‐constant dependencies on temperature were observed at 923 K. Above this temperature the changes in occupation of the Ca/Eu sites occur, exhibiting a tendency towards a more uniform Eu distribution over the three Ca/Eu sites. Possible structural origins of the observed thermal expansion anisotropy are discussed.

中文翻译：

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阳离子分布随温度的变化及其对Ca3Eu2（BO3）4热膨胀的影响。

原硼酸钙euro钙Ca ₃ Eu ₂（BO ₃）_4的结构使用在环境条件以及高温下在ID22光束线（ESRF）上收集的高分辨率粉末X射线衍射数据确定。通过Rietveld精炼，可以确定晶格常数和结构细节，包括三个阳离子位点的Ca / Eu比及其随温度的变化。发现明显的热膨胀各向异性，并且在923 K处观察到晶格常数对温度的依赖性的斜率变化。在此温度以上，Ca / Eu位置的占据发生变化，表现出在这三个位置上Eu分布更均匀的趋势Ca / Eu网站。讨论了观察到的热膨胀各向异性的可能的结构起源。