Cu2Mg5Sn5Se16 – the first selenospinel of the A2B5C5X16 type

A new member of the A2B5C5X16 family of compounds – the first one containing Se – has been synthesized. Following a one-step mechanochemical synthesis route, starting from the binary selenides and Mg metal, Cu2Mg5Sn5Se16 has been obtained. Structural evaluation was carried out using X-ray diffraction with subsequent Rietveld refinement. Cu2Mg5Sn5Se16 adopts the spinel type with space group Fd 3 ‾ $\overline{3}$ m and exhibits a statistical distribution of Cu, Mg, and Sn on Wyckoff position 16d whereas Wyckoff position 8a is only occupied by Mg. Despite the fact that structures containing MgSe4 tetrahedra are rare in the literature, it appeared to be the most plausible way of distributing the cations in this compound.