We study phase equilibria in a section of 7.14 at.% La in the La–Cu–Si ternary system at 870°K by the methods of X-ray phase diffraction and structural analysis. The existence of two new LaCu_9.61Si_3.39 and LaCu_8.37Si_4.63 ternary compounds is established and their crystal structures are studied by the X-ray powder diffraction method. Both compounds are the first representatives of the NaZn₁₃ structural type and its CeNi_8.5Si_4.5 tetragonally deformed superstructure in the R–Cu–Si systems. We also analyze structural transformations based on the NaZn₁₃ structural type, as well as the affinity of the investigated compounds with the structures of binary and ternary lanthanum and copper silicides with respect to the closest coordination surrounding of the least electronegative atoms. Finally, we illustrate structural relationships between the investigated compounds and simple crystal structures (of copper and silicon) with which they are in phase equilibria in the La–Cu–Si system.

我们通过X射线相衍射和结构分析方法研究了870°K下La–Cu–Si三元体系中7.14 at。％La的截面中的相平衡。建立了两种新的LaCu _9.61 Si _3.39和LaCu _8.37 Si _4.63三元化合物的存在，并通过X射线粉末衍射法研究了它们的晶体结构。这两种化合物都是R–Cu–Si系统中NaZn ₁₃结构类型及其CeNi _8.5 Si _4.5方形变形上层结构的首个代表。我们还分析了基于NaZn _13的结构转变化合物的结构类型，以及相对于最小负电性原子最近的配位关系而言，所研究化合物与二元和三元镧和硅化铜结构的亲和力。最后，我们说明了所研究的化合物与简单的晶体结构（铜和硅）之间的结构关系，它们在La–Cu–Si系统中处于相平衡状态。