A DFT study on pressure dependency of TiC and ZrC properties: Interconnecting elastic constants, thermodynamic, and mechanical properties

Abstract

We performed first principle calculations to investigate pressure dependency of mechanical and thermal properties of TiC and ZrC through their correlation with elastic constants and enthalpy. We cover mechanical stability, phase transitions, elastic properties, brittleness and ductility, hardness, anisotropy factors, sound velocity, thermal conductivity, and Debye temperature. We implemented different correlating models associated with these parameters, in order to calculate them in different pressures. We show that NaCl (B1) is the most stable structure of TiC and ZrC even at high pressures. Shear deformation was not observed in B1 structure up to 231 GPa (TiC) and 162 GPa (ZrC). Transition pressure was calculated to be 298.7 and 589.7 GPa for TiC and ZrC, respectively. TiC shows higher resistance than ZrC against applied pressure. Higher elastic constants of TiC respect to ZrC at different pressures denote that TiC is stiffer than ZrC. We report that TiC and ZrC are brittle in pressures up to 50 and 40 GPa, respectively. By increasing pressure, ductility increases, however, the hardness of the ZrC drops faster than in TiC. Anisotropy factors, elastic properties on different crystallographic planes, sound velocities, minimum thermal conductivity, and Debye temperature in both of TiC and ZrC crystals increase by pressure.