T(Z) DIAGRAM OF THE MN3ZGA2(1-Z)SE3 SYSTEM

The T(z) phase diagram of the system Mn3zGa2(1-z)Se3 is determined fro m differential thermal analysis and X-ray diffraction measurements. Si ngle-phase solid solutions with an adamantine structure are found to o ccur in the composition range 0 < z < 0.26 at temperatures below 660-d egrees-C. but extended out to z = 0.57 above that temperature. Below 6 60-degrees-C, two separate ordered structures occur, corresponding to the monoclinic ordered structure of Ga2Se3 and to the tetragonal one o f MnGa2Se4, while between these two there is a partially ordered zincb lende form characterized by stacking faults, as previously observed fo r Ga2Se3. This phase extends above 660-degrees-C but at higher values of z changes to a disordered zincblende form.