The Isothermal Section of the Phase Diagram of Dy-Sm-Ge Ternary System at 873 K

Abstract

The interaction of components in the Dy-Sm-Ge system at 873 K was investigated by means of x-ray phase and structural analyses, microstructural analysis and energy dispersive x-ray spectroscopy. The existence of the continuous solid solutions between the isostructural binary germanides of the Dy1−xSmxGe (CrB-type), Dy5-xSmxGe4 (Sm5Ge4-type) and Dy5-xSmxGe3 (Mn5Si3-type) were established. The limited solid solutions based on the binary germanides of the SmGe2 (α-ThSi2-type), DyGe2 (TbGe2-type) and Dy11Ge10 (Ho11Ge10-type) are formed. The solubility of Dy in SmGe2 is 15 at.%, Sm in DyGe2 and Dy11Ge10 − 10 at.%, Sm. Two ternary SmxDy1−xGe1.5 (x = 0.15-0.50) and Sm2Dy2Ge7 compounds were found. SmxDy1−xGe1.5 crystallizes in AlB2 structure type. The crystal structure of the new ternary compound of the Sm2Dy2Ge7 (ordered superstructure to Nd4Ge7-type, Pearson symbol oS44, space group C2221, a = 0.5942(1), b = 1.3823(4), c = 1.1801(3) nm, V = 0.9694 nm3) was investigated by means of x-ray single crystal diffraction. The germanium atoms form 3D anionic network the existence of which was confirmed by electronic structure calculations.