Impact of Point Defects and V Doping on the Thermodynamic Properties of TiB: First‐Principles Calculations

Abstract

In this work, the thermodynamic properties of TiB with B‐vacancy, Ti‐vacancy, V‐substitutional doping, and V‐interstitial doping under high temperature and high pressure are systematically analyzed using first‐principles calculations. The presence of both types of vacancies leads to a decreasing trend for the volume, whereas the different forms of V doping could cause lattice distortion and affect supercell volume. In addition, regardless of the vacancy or doping‐based modification of TiB, its constant volume heat capacity increases with the temperature and approaches the Dulong–Petit limit, while the constant pressure heat capacity slowly decreases by increasing the pressure. The presence of vacancies also affects the thermal expansion coefficient of TiB, thereby regulating its high‐temperature ductility, and the V interstitial doping approach is beneficial for improving the high‐temperature ductility of TiB. The Debye temperature of TiB with vacancies is proven more sensitive to pressure changes than the temperature, where the V doping has a significant impact on the Debye temperature of TiB. And the Debye temperature of TiB with interstitial V atoms is lower than that of TiB with substitutional V atoms, indicating that the interaction force is higher than that of the interstitial sites.