Abstract:First principles calculation and quasi-harmonic Debye model were used to obtain more physical properties of zirconium carbide under high temperature and high pressure. The results show that the B1 structure of ZrC is energetically more favorable with lower heat of formation than the B2 structure, and that mechanical instability and positive heat of formation induce the inexistence of the B2 structure at normal pressure. It is also found that the B1 structure would transform to the B2 structure under high pressure below the critical point of V/V₀=0.570. In addition, various thermodynamic and elastic properties of ZrC are obtained within the temperature range of 0-3000 K and the pressure range of 0-100 GPa. The calculated results not only are discussed and understood in terms of electronic structures, but also agree well with corresponding experimental data in the literature.

Key words: ZrC; phase transition; thermodynamic properties; elastic properties; first principles calculation