新稀土金属间化合物晶体结构及高温晶格热膨胀性能研究

[目的]研究稀土-过渡族金属合金体系中的新稀土金属间化合物,挖掘稀土合金与化合物的新应用。[方法]利用扫描电子显微镜和能谱仪分析合金样品及其组成物相的成分,采用X射线粉末衍射技术研究和测定新金属间化合物的晶体结构及高温晶格热膨胀性能,并对所研究的新金属间化合物的高温热膨胀性能进行总结分析。[结果]不同的合金元素可以形成结构类型相同的晶体结构,得到了部分新金属间化合物的晶格热膨胀系数,这些新稀土金属间化合物的平均晶格热膨胀系数在10~(-6)到10~(-5)数量级之间,它们的平均单胞体积热膨胀系数也在同一数量级。[结论]化学性质相近的合金元素可以相互替代形成同构型金属间化合物。利用X射线粉末衍射同构法可测定新化合物的晶体结构,该法适用于解析二元、三元乃至多元新化合物的晶体结构。所研究的新稀土金属间化合物的热膨胀系数分别满足其各自所属晶系的热膨胀关系。

Study on the Crystal Structure and the Lattice Thermal Expansion Properties of Some Novel Rare Earth Intermetallic Compounds

[Objective] Researches on new rare earth intermetallic compounds of rare earth-transition metal alloy systems were carried out in order to explore the new potential applications of rare earth alloys and compounds.[Methods] The compositions of the alloy samples and phase components were analyzed by scanning electronic microscopy with the aid of energy dispersive spectroscopy.The crystal structures of some new compounds found in alloy phase diagram studies were determined by powder X-ray diffraction isomorphic method.The coefficients of average lattice thermal expansion and unit cell volume of some selected novel rare earth compounds were obtained by using high temperature X-ray diffraction technique.Analysis on the lattice thermal expansion of some new intermetallic compounds was performed and the properties of high temperature thermal expansion of the new intermetallic compound were summarized.[Results] Different alloying elements can form isostructural intermetallic compounds. The coefficients of the lattice thermal expansion properties were obtained from some novel intermetallic compounds, of which the order of magnitude of the coefficients of average lattice thermal expansion was about 10^-6 to 10^-5 and that of unit cell volume stood at the same scale.[Conclusion] Alloying elements with similar chemical properties can be substituted with each other to form isostructural intermetallic compounds. The crystal structures of some new compounds can be determined by powder X-ray diffraction isomorphic method, which can be applied to binary, ternary even multi-component new compounds.The lattice thermal expansion coefficients obey the thermal expansion laws of their crystal systems.