Etude des propriétés structurales, électroniques et thermodynamiques des composés Cs2MF6 (M= Cr et Ni)

Abstract

Ab- initio calculations have been performed on the structural, electronic, elastic and thermodynamic properties of Cs6MF6 compounds (M=Cr and Ni) using the formalism of the density functional theory (DFT). The exchange-correlation potential has been treated by the generalized gradient approximation (GGA) based on the Perdew-Burke-Ernzerhof function (PBE) implemented in the Quantum ESPRESSO code. The elastic constants of the compound have been estimated and the results obtained verify the stability criteria. The electronic properties of the compounds indicate that the compound Cs2CrF6is a semi- metal and the compound Cs2NiF6behaves as a semiconductor. Using the the quasi-harmonic Debye model implemented in the Gibbs 2 program, the thermodynamic properties of Cs2CrF6 and Cs2NiF6compounds such as the heatcapacity (CV) and the thermal expansion (α) have also been calculated and analyzed