X-ray diffraction, 119Sn Mössbauer and thermal study of SnSe–Bi2Se3 system

The phase equilibrium diagram of the SnSe–Bi2Se3 system has been re-investigated using X-ray powder diffraction, thermal analysis (DTA and DSC) and 119Sn Mössbauer spectroscopy data. It shows solid solutions based on Bi2Se3 and SnSe (α and β forms) and three intermediate phases: well-defined, SnBi4Se7, SnBi4Se7, and a new phase Sn2Bi2Se5. The new phase Sn2Bi2Se5 exists in the composition range 25–55 mol% Bi2Se3. Its structure is still under study. However, 119Sn Mössbauer spectroscopy study of the latter allowed to achieve a well knowledge of the local environment of tin atoms and could contribute to the actual structural study.