The detailed orbital-decomposed electronic structures of tetragonal ZrO2

Abstract: The detailed orbital-decomposed electronic structures of the tetragonal zirconia have been investigated by using the first-principles projector augmented wave (PAW) potential within the generalized gradient approximation (GGA) as well as taking into account the on-site Coulomb repulsive interaction (GGA+U). The deviation of the minimization energy from d z =0 to d z =±0.032 for experimental lattice constants (a=3.605Å and c=5.180Å) confirms the alternating displacement of the oxygen atoms, which causes half of the ZrO bonds stronger and the other half weaker compared with the bonds in symmetric (d z =0) zirconia. The distorted tetragonal environment of the eight oxygen anions around Zr site splits the five-fold degenerate d states of a free Zr atom into triply degenerate t2g (d xy , d yz and d zx ) states and doubly degenerate e g ( and ) states. The additional covalent character upon Zr-O ionic bonds are resulted from the hybridization between the O(2s), O(2p) and Zr(5s), triply degenerate t2g (d xy , d yz and d zx ) states of Zr(4d). The O(2s) and O(2p) states are clearly separated and no hybrid bonding states are formed. [Copyright &y& Elsevier]