Electronic structure and vacancy formation of Li₃N

The electronic structure and vacancy formation of Li₃N were studied using first principles methods. We found Li₃N exhibits strong ionic character with slight covalent bonding between N and Li. The Li vacancy formation energy decreases with an increase in nitrogen partial pressure, while the N vacancy formation energy increases with increasing nitrogen partial pressure. The Li(2) site vacancy is found to have the lowest formation energy under nitrogen-rich conditions. Formation of V^-_Li(2) brings about delocalization of valence electrons, and reduces the band gap by 0.2 eV. These results suggest potential ways to enhance vacancy concentration in Li₃N for higher ionic conductivity. © 2009 American Institute of Physics.