Pressure effect on the structural, elastic and electronic properties of Nb2AC ( A = S and In) phases; ab initio study

The structural parameters, elastic and electronic properties of Nb(2)AC ( A = S and In) phases were investigated under pressure using first-principles plane-wave pseudopotential density functional theory within the generalized gradient approximation. We find that the effect of pressure on the crystal structure reflects in a compression of the unit cell-volume, mainly along the c-axis. On the other hand, the elastic constants, elastic modulus and the Debye temperature theta(D) increase monotonically as the pressure increases. The relationship between brittleness and ductility shows that Nb2AC are brittle at 0 GPa and only the Nb2SC phase tended to be ductile under pressure from 4 GPa to 10 GPa. Finally, we find that the density of states at the Fermi level decrease in the Nb2InC phase and increase in Nb2SC phase under pressure. (C) 2013 Elsevier B.V. All rights reserved.