First-principles calculations on the structural, elastic and electronic properties of a class of ternary carbides: A survey investigation

Abstract First-principles calculations were carried out to investigate the structural, elastic and electronic properties of a series of ternary carbides with the formula of RTM C 2 ( R  = Sc, Y, Zr; TM  = Ti, V, Cr, Mn, Fe, Co, Ni, Cu). All the carbides are thermodynamically and mechanically stable. Most of them have cohesive energies and formation enthalpies comparable to those of the previously reported ScCrC 2 . Their lattice constants are highly dependent on the chemical composition. Their C C bond lengths in the unit cell range widely from 1.3577 A for YNiC 2 to 1.8381 A for ZrTiC 2 . All the carbides are nonmagnetic or antiferromagnetic. The slight difference of composition can be reflected in the electronic structure. Generally, the bulk modulus of an early transition metal ( TM ) containing carbide is higher than that of a late TM containing one. The low hardness and good ductility of the late TM containing carbides are attributed to the delocalized TM d-electrons. Finally, the simple rules for designing ductile ceramics were proposed.