Ab initio study of the bonding and elastic properties of Ti2CdC

The chemical bonding and elastic properties of Ti2CdC were investigated by means of a first-principles pseudopotential total energy method. The calculated results for the lattice constants and internal coordinate agree with experimental values very well. Ti2CdC is conducting, and the Cd-d states have little effect on the chemical bonding. The elastic properties were estimated from the individual elastic constants by Voigt approximation. The calculated shear-modulus of Ti2CdC, 70 GPa, is the lowest value among all MAX phases. The lower shear-modulus and shear-modulus-to-bulk-modulus ratio are related to the weaker Ti–Cd bond, which indicates the lower coefficient of friction. This suggests that Ti2CdC would be a potential electrical frictional material.