Temperature variation of lattice parameters and thermal expansion coefficients of the compound ZnGa 2Se 4

Abstract

X-ray powder diffraction measurements on ZnGa 2Se 4, a II-III 2-VI 4 semiconductor compound, were made in the temperature range between 300 K and 700 K, a region in which this material has a defect tetragonal structure. From the analysis of the X-ray diffraction lines, accurate lattice parameter values were determined as a function of temperature. These results allowed the evaluation of the thermal expansion coefficients of the corresponding parameters. The observed increase, with the temperature, of the tetragonal deformation δ(= 2 − c a ) as well as of the crystal anisotropy A a (= α a − α c , with α a > α c ) was then explained by using the relations proposed by Abrahams and Bernstein.