Amorphous zirconia: ab initio molecular dynamics simulations

We investigate the short-range order of the liquid and amorphous zirconia using an ab initio molecular dynamics technique. Both forms of zirconia are projected to be structurally close to each other. The amorphous network has predominantly seven-fold coordinated Zr atoms (∼%65), and three-fold and four-fold coordinated O atoms (∼46%), and hence it resembles locally the monoclinic zirconia phase. Within the known limitations of the DFT-GGA calculation, the liquid state is predicted to be semi-metal, whereas the amorphous form is projected to be semiconductor having a band gap energy of ∼3.5 eV. We find an asymmetry in localisation of the band tail states. On the basis of this finding, we discuss possible distinctions in n-type and p-type doping in amorphous zirconia.