Phase equilibria in the CdAs2–Cd3As2–MnAs ternary system

We determined, using a set of physicochemical methods, including X-ray powder diffraction (XRD), differential thermal analysis, and microstructure studies, that the CdAs2–Cd3As2–MnAs ternary system is bounded by three eutectic-type quasi-binary sections: Cd3As2–MnAs, CdAs2–MnAs, and Cd3As2–CdAs2. For Cd3As2–MnAs and CdAs2–MnAs sections, the eutectic coordinates are, respectively, 75 mol % Cd3As2 + 25 mol % MnAs, Tm.eut = 604°C; and 92 mol % CdAs2 + 8 mol % MnAs, Tm.eut = 608°C. These are rod eutectics. Manganese solubilities in Cd3As2 and CdAs2 phases are insignificant and, according to XRD and SEM, they do not exceed 1 at %. The binary eutectics of the quasi-binary sections form ternary eutectic Cd3As2 + CdAs2 + MnAs, whose average composition as probed by SEM is 34.5 at % Cd, 63 at % Cd and 2.5 at % As and Tm.eut = 600°C. Cadmium and manganese arsenide alloys are ferromagnets with the Curie point at ~320 K. The magnetic and electric properties are due to ferromagnetic MnAs microinclusions.