Impact of the point defects and V doped on the thermodynamic properties of TiB: first‐principles calculations

In this work, the impact of point defects and V doped on the thermodynamic properties of TiB was calculated using the ultra‐soft pseudo‐potential approach of the plane wave based on the density functional theory (DFT). More specifically, based on the Quasi‐harmonic Debye model, the volume, heat capacity, thermal expansion coefficient, and Debye temperature of TiB with B‐vacancy, Ti‐vacancy, V substitutional doped, and V interstitial doped under high temperature and high pressure were systematically analyzed. From the calculated results, it was indicated that the presence of both types of vacancies leads to a decreasing trend for the volume. Particularly, the different forms of V doping could cause lattice distortion and affected supercell volume, whereas their volume was positively correlated with the temperature and negatively correlated with the pressure. The V interstitial doped led to an increased in both the constant volume heat capacity and the constant pressure heat capacity of TiB. In addition, regardless of the vacancy or doping‐based modification of TiB, its constant volume heat capacity increased with the temperature and approached the Dulong‐Petit limit, while the constant pressure heat capacity slowly decreased by increasing the pressure. The presence of vacancies also affected the thermal expansion coefficient of TiB, thereby regulated its high‐temperature ductility. The V interstitial doping approach was beneficial for improving the high‐temperature ductility of TiB, whereas substitutional doping was led to a decreasing trend at high pressure. The Debye temperature of TiB with vacancies was proven more sensitive to pressure changes than the temperature. On the contrary, the V doping had a significant impact on the Debye temperature of TiB, and the Debye temperature of TiB with interstitial V atoms was lower than that of TiB with substitutional V atoms, indicating that the interaction force between the substitutional atoms was higher than that of the interstitial sites.This article is protected by copyright. All rights reserved.