The phase diagram of the Sr-Ge system

The phase diagram of the Sr-Ge system has been investigated across almost the whole composition range (0-85 at.% Ge) using differential thermal analysis and X-ray diffraction. Four intermediate phases exist: Sr2Ge (PbCl2-type, orthorhombic oP12-Pnma), Sr5Ge3 (Cr5B3-type, tetragonal tI32-I4/mcm), SrGe (CrB-type, orthorhombic oC8-Cmcm) and SrGe2 (BaSi2-type, orthorhombic oP24-Pnma). A further intermediate phase, observed only at high temperature above 985 °C, crystallizes with a defective AlB2-type structure. Four eutectics occur in the system: about 5 at.% Ge at 740 °C, 42 at.% Ge at 1100 °C, 61 at.% Ge at 965 °C and 85 at.% Ge at 755 °C. As a whole, the Sr-Ge system appears very similar to the Sr-Si one.