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用差热分析和X射线衍射的方法研究了EuI2 KI二元体系在 3× 10 - 4 Pa压强下的低压相图。实测相图显示 ,该二元体系存在一个同份熔化化合物KEu2 I5 和一个异份熔化化合物K4EuI6 ,两个三相共晶点的温度和成分分别为 737K ,2 0 %KI和 713K ,6 0 %KI。X射线粉末衍射的结果表明KEu2 I5 的晶体结构参数与文献数据十分吻合。本文还讨论了实测相图的误差来源 ,并由相图计算出EuI2 的熔化热为2 10 12J·mol- 1 。
The low pressure phase diagram of EuI2 KI binary system at 3 × 10 -4 Pa was studied by means of DTA and XRD. The measured phase diagram shows that the binary system has a same melting compound KEu2 I5 and a different melting compound K4EuI6, the temperature and composition of the two three-phase eutectic points are 737K, 20% KI and 713K, 60% KI. X-ray powder diffraction results show that the crystal structure of KEu2 I5 parameters and literature data are in good agreement. The paper also discusses the sources of error of the measured phase diagram and calculates the melting heat of EuI2 from the phase diagram to be 2 10 12 J · mol -1.