First Principles Study of the Thermodynamic Properties of TiB_2

The thermodynamic properties of hexagonal TiB2 at high temperature and pressure are calculated by using first principles combined with quasi-harmonic Debye model,including the temperature dependence of the lattice parameter,the bulk modulus B0,the heat capacity Cp and the entropy S under ambient pressure.Meanwhile,the relationship of the temperature with the heat capacity Cp,the entropy S,the coefficient of volume expansion α,the Debye temperature Θ and the heat capacity CV expansion coefficient under different pressures is successfully obtained.The results show the calculated heat capacity Cp and entropy S under ambient pressure are in good agreement with experimental measurements.