Phase equilibria in the ZnGeAs2–MnAs system

The ZnGeAs2–MnAs system is a eutectic-type system as determined by X-ray powder diffraction, DTA, and microstructure observation, with the eutectic coordinates: 61 mol % ZnGeAs2 mol %, 39 mol % MnAs, and Tm = 816°C. The eutectic is a lamellar eutectic as shown by microstructure examination. A characteristic feature of the system is a small mutual solubility of the components. Precision analysis of diffraction patterns enabled us to refine unit cell parameters for cubic and tetragonal ZnGeAs2 phases. MnAs in alloys is shown to consist of a hexagonal phase and a orthorhombic phase. ZnGeAs2 and MnAs alloys are ferromagnets (TC ~ 320 K). Their magnetization increases in response to increasing MnAs content.