Study of Bi2CaX2 (X=Mg and Mn) compounds: A first-principle approach

Abstract

In this paper, we are studied the electronic, structural, optical, dielectric and thermodynamic properties of Bi2CaX2 (X = Mg and Mn) with full-potential linearized augmented plane-wave (FP-LAPW) method, by using the “WIEN2k” code. The lattice constants of Bi2CaX2 compounds are calculated by using the GGA-PBE approximation. We are found the first one is semi-conductor character with direct gap Eg = 0.580 eV and the second is metallic character. The reflectivity, dielectric function, absorption coefficient, energy loss function and optical conductivity are obtained. The values obtained at room temperature and at P = 0 GPa are 215.4997 and 180.8549 J/(mol.K) for Bi2CaMg2 and Bi2CaMn2, respectively. This large entropy indicates that these compounds are not ordered. The thermal expansion coefficient, the thermal entropy and the Debye temperatures have also been determined. The elastic parameters are also studied and discussed.