Theoretical study of nitrogen vacancies in Ti4AIN3 -: art. no. 031911

We have investigated the energetics of the N vacancy formation in Ti4AlN3 by ab initio calculations. We identify N 2a sites (Wyckoff notation) in Ti4AlN2.75 as the most probable vacancy sites based on the energetics of vacancy formation. Furthermore, Ti4AlN3 does not exhibit any states at the Fermi level. Introducing N vacancies causes states to appear at the Fermi level, which may enable electron transport. Recently measured conductivity data [Finkel et al., Phys. Rev. B 67, 235108 (2003)] for Ti4AlN3 can be understood based on our calculations. (C) 2005 American Institute of Physics.