The energetics of N-vacancy formation were investigated by means of ab initio calculations. It was deduced that N 2a sites (Wyckoff notation) in Ti4AlN2.75 were the most probable vacancy sites, as based upon the energetics of vacancy formation. The Ti4AlN3 did not exhibit any states at the Fermi level. Introducing N vacancies caused states to appear at the Fermi level; which might enable electron transport. It was concluded that recent conductivity data for Ti4AlN3 could be understood on the basis of these calculations.

Theoretical Study of Nitrogen Vacancies in Ti4AlN3. D.Music, R.Ahuja, J.M.Schneider: Applied Physics Letters, 2005, 86[3], 031911 (3pp)