Crystallographic properties of the MnGa2Se4 compound under high pressure

Abstract

X-ray diffraction measurements on MnGa2Se4, a II-III2-VI4 magnetic semiconductor compound, are made as a function of pressure up to 25GPa. It is found that in the range of 0<P<12GPa the structure is a defect tetragonal; in the range between 12 and 14GPa a two phase field α+NaCl type exists. It is found that at about 14GPa 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 δ, χa, and χc 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 3GPa, a symmetry change, from an ordered tetragonal to a disordered tetragonal structure, occurs.