The T(y) phase diagram of the alloys CuInyGa1−ySe2, prepared by the chemical vapor deposition method, is obtained from X‐ray diffraction and differential thermal analyses. It is found that in addition to the chalcopyrite structure, a zincblende In2Se3‐rich phase and a zincblende Ga2Se3‐rich plus liquid two‐phase field, are obtained. Also it is found that the variation of the lattice parameter ratio c/a is not linear with composition but varies from 1.96 to 2.00 as y is increased from 0.0 to 0.6 and c/a being equal to 2.00 in the composition range 0.6 ⪅ y ⪅ 1.0. The energy gap values, obtained from optical absorption measurements, follow a second‐order equation in y giving a downward bowing parameter of about 0.15 eV.

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International audienceX-ray diffraction measurements on MnGa2Se4, a II-III2-VI4 magnetic semiconductor compound, are made as a function of pressure up to 25 GPa. It is found that in the range of 0P12 GPa the structure is a defect tetragonal; in the range between 12 and 14 GPa a two phase field +NaCl type exists. It is found that at about 14 GPa a transition to the cubic NaCl-type structure occurs and it appeared that this transition is irreversible. From the analysis of the x-ray diffraction lines, lattice parameter values are determined as a function of pressure. These results allow the evaluation of the compressibility coefficients of the corresponding parameters. The observed behavior of , a, and c with pressure are explained by using the relations proposed by Abrahams and Bernstein J. Chem. Phys. 52, 5607 1970. It is found that at about 3 GPa, a symmetry change, from an ordered tetragonal to a disordered tetragonal structure, occur

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