Electronic structure and stability of the transition metal oxide Ni₂Ti₄O

The electronic structure of Ni₂Ti₄O is studied using first-principles calculations based on the linear-muffin-tin-orbital method. The role of oxygen in stabilizing the metallic NiTi₂-type structure is analysed by site-projected energy calculations which indicate that the Ti(f) sites with nonicosahedral symmetry determine the structural stability of Ni₂Ti₄O. The origin of this behaviour, contrary to that found for NiTi₂, is due to the effects of 2p(O)-3d(Ti(f)) hybridization.