First-principles study of carbon vacancy in Ta4AlC3

Abstract

We have investigated the carbon mono-vacancy in Ta4AlC 3 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. © 2008 The Japan Institute of Metals.