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

First-principles calculations were carried out to investigate the structural, elastic and electronic properties of a series of ternary carbides with the formula of RTMC2 (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 ScCrC2. Their lattice constants are highly dependent on the chemical composition. Their C-C bond lengths in the unit cell range widely from 1.3577 angstrom for YNiC2 to 1.8381 angstrom for ZrTiC2. 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. (C) 2016 Elsevier Ltd. All rights reserved.