Phase diagram of the ZnSnAs2-MnAs system

Six equilibrium samples of (1 − x)ZnSnAs2 + xMnAs (x = 0, 0.1, … 0.5 mol.%) and one quenched sample of 0.8ZnSnAs2 + 0.2MnAs were synthesized. The samples were studied with X-ray, DTA, MFM and SEM. The system ZnSnAs2-MnAs has eutectic point with coordinates 45 ± 2 mol.% MnAs and 744 ± 10 °C. The eutectic compound contains isolated, practically round shape inclusions of MnAs in the host ZnSnAs2. Based on the earlier investigations, we predict negative magnetoresistance effect in this semiconductor-ferromagnet compound with nanogranular structures. The lattice parameters of ZnSnAs2 without manganese arsenide and ZnSnAs2 + MnAs are similar, meaning MnAs does not influence the lattice parameters. Therefore one can make conclusion that solubility of the MnAs in ZnSnAs2 is low. The lattice parameters are a = 5.8509 Å, c = 11.7135 Å for tetragonal and a = 5.8558 Å for cubic symmetry. The density of the ZnSnAs2 calculated from the HR-XRD is 5.5314 g/cm3 for tetragonal and 5.5230 g/cm3 for cubic structure.