The phase diagram of the Sr–Ge system

Abstract

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: Sr 2Ge (PbCl 2-type, orthorhombic oP12- Pnma), Sr 5Ge 3 (Cr 5B 3-type, tetragonal tI32- I4/ mcm), SrGe (CrB-type, orthorhombic oC8- Cmcm) and SrGe 2 (BaSi 2-type, orthorhombic oP24- Pnma). A further intermediate phase, observed only at high temperature above 985 °C, crystallizes with a defective AlB 2-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.