First-principle calculations of ductile CeAg intermetallic compound

Abstract

The first-principle calculations were performed to investigate the structural, mechanical, electronic and thermal properties of the binary ductile intermetallic compound CeAg with B2 (CsCl) structure. The calculated value of lattice constant a0 for CeAg with generalized gradient approximation is 3.713 Å, which is in better agreement with experimental data than local spin density approximation. The negative energy of formation implies that CeAg with B2 structure is thermodynamically stable phase. The greater separation between the d bands of Ce and Ag results in weaker bond hybridization of Ce d—Ag d, which prevents formation of directional covalent bonding. The three independent elastic constants (C11, C12 and C44) are derived and the bulk modulus, shear modulus, elastic modulus, anisotropy factor, and Poisson ratio are determined to be 57.6 GPa, 15.8 GPa, 43.4 GPa, 3.15 and 0.374, respectively. The elastic constants meet all the mechanical stability criteria. The value of Pugh's criterion is 3.65. The ductility of CeAg is predicted if Pugh's criterion is greater than 1.75. Furthermore, the variations of volume, bulk modulus, heat capacity, and thermal expansion coefficient with temperature and/or pressure were calculated and discussed.