First-Principles Study of Carbon Vacancy in Ta₄AlC₃

Abstract

We have investigated the carbon mono-vacancy in Ta₄AlC₃ by first-principles calculations. We identify the 2a sites as the probable carbon vacancy sites in Ta₄AlC₃ based on the energetics of vacancy formation. It was found that introducing carbon vacancies decreased the phase stability of Ta₄AlC₃. There are no significant changes in volume by introducing carbon vacancy. However, the bulk modulus decreased when introducing carbon vacancy. The differences in density of states of Ta₄AlC₃ with and without carbon vacancies are analyzed. Some vacancy peaks near the Fermi level were observed. Additionally, the density of states at the Fermi level increases by introducing carbon vacancies, which may be of benefit to the electron transport in Ta₄AlC₃.