Lattice parameters values and phase diagram for the Cu2Zn1−zMnzGeSe4 alloy system

The T(z) phase diagram of the Cu2Zn1−zMnzGeSe4 alloy system is obtained from X-ray diffraction and differential thermal analysis DTA. At room temperature, the X-ray diffraction data showed that samples in the ranges 0 < z < 0.375 had the tetragonal stannite α structure (I4¯2m), while for 0.725 < z ⩽ 1 the wurtz-stannite δ structure (Pmn21). The α and δ fields are separated by a relative wide three-phase field (α + δ + MnSe2). The DTA thermograms were used to construct the phase diagram of the Cu2Zn1−zMnzGeSe4 alloy system. It was confirmed that the Cu2ZnGeSe4 and Cu2MnGeSe4 compounds melt incongruently. It was observed that undercooling effects occur for samples in the range 0.725 < z < 0.925.