Effect of carbon content and electronic strong correlation on the mechanical and thermodynamic properties of ytterbium carbides

摘要: The mechanical and thermodynamic properties of four ytterbium carbides with increasing carbon content have been examined using ab initio calculations based on density functional theory. In order to describe the strong on-site Coulomb repulsion among localized 4f electrons, generalized gradient approximation plus a Hubbard parameter (GGA + U) formalisms adopted for exchange correlation term. elastic constants YbC, Yb2C3, YbC2, YbC6 are related U. bulk modulus B, shear G, Young's E evaluated through Voigt–Reuss–Hill approximation. Among carbides, yields largest E, YbC2 exhibits relatively soft ductile characteristics. Mechanical anisotropy was estimated several anisotropic indexes factors. property is more evident than that B. A phonon calculation reveals stability YbC6, which consistent experimental observations.