The phases in the lanthanum-germanium system

Conclusions

The lanthanum-germanium system was investigated. The existence of four, previously established compounds was confirmed. The width of the homogeneity region of the lanthanum-rich compounds is narrow. The width of the homogeneity region of lanthanum digermanide extends over the composition range LaGe-LaGe_2.0, which corresponds to germanium contents of 42–51%. Lanthanum digermanide exhibits two modifications with crystalline structures of the α-ThSi₂ and α-GdSi₂ types, which are capable of independent existence at room temperature. The phase with an α-GdSi₂ type structure forms at germanium contents corresponding to the compositions LaGe_1.8-LaGe_2.0, while the α-ThSi₂ type structure forms at germanium contents lower than theoretical (42–45 wt.%). At the composition LaGe_1.7, the phases with the α-GdSi₂ and α-ThSi₂ type structures coexist.