The thermal expansion of orthorhombic CaFe 2 O 4 -type β-CaCr 2 O 4 , ellinaite, was studied by high temperature in-situ synchrotron X-ray diffraction measurements in the temperature range of 301–973 K at atmospheric pressure. Based on the obtained data, the thermal expansion coefficients of β-CaCr 2 O 4 were determined as 2.84(3) × 10 –5 K −1 , 1.08(1) × 10 –5 K −1 , 0.79(1) × 10 –5 K −1 , 0.99(1) × 10 –5 K −1 for volume, a -, b - and c axis, respectively. An anisotropic behavior was observed because the axial expansivity for the b axis is smaller than those of the a - and c axis. Combined with available experimental results, the isobaric heat capacity ( C p ) of β-CaCr 2 O 4 was evaluated by using a Kieffer’s model with Raman spectroscopy data and compared with previous studies. The isochoric heat capacity ( C v ), standard entropy ( S 0 298 ) and Debye temperature (θ D ) of β-CaCr 2 O 4 were also determined.

中文翻译：

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Elinaite (β-CaCr2O4) 的热膨胀：原位高温 X 射线衍射研究

通过高温原位同步加速器 X 射线衍射测量在大气压下 301-973 K 的温度范围内研究了斜方晶 CaFe 2 O 4 型 β-CaCr 2 O 4 的热膨胀。根据获得的数据，β-CaCr 2 O 4 的热膨胀系数确定为 2.84(3) × 10 –5 K -1 , 1.08(1) × 10 –5 K -1 , 0.79(1) × 10 –5 K -1 , 0.99(1) × 10 –5 K -1 分别用于体积、a -、b​​ - 和 c 轴。观察到各向异性行为，因为 b 轴的轴向膨胀率小于 a - 和 c 轴的轴向膨胀率。结合现有的实验结果，β-CaCr 2 O 4 的等压热容（C p ）通过使用具有拉曼光谱数据的基弗模型进行评估，并与之前的研究进行比较。等容热容 ( C v )，