Electronic, mechanical, phase transition and thermo-physical properties of TiC, ZrC and HfC: High pressure computational study

Structural, electronic, mechanical and thermo-physical properties of refractory carbides (TiC, ZrC and HfC) have been investigated in the stable B1 as well as high pressure B2 phase along with the high pressure phase transition in these materials by two different pseudo- and full-potential approaches. The results are compared with experiments to adjudge the effectiveness of both approaches. Band structure and DOS calculations provide evidence for metallic (finite DOS at E-F) and covalent (C (p)-TM (d) hybridization) bonding in these materials in both phases. Ionic bonding is also revealed from charge density plots. Covalent nature dominates in B1 phase while ionic bonding in B2 phase. The elastic constants show the mechanical stability of these carbides in B1 phase and instability in B2 phase. These materials are brittle and anisotropic in B1 phase. Elastic wave velocities and the Debye temperatures have also been reported. The present results show good agreement with the measured data. However, some of the calculations are reported for the first-time. (C) 2013 Elsevier B.V. All rights reserved.