Electronic structure and electron energy-loss spectroscopy of ZrO2 zirconia

TitleElectronic structure and electron energy-loss spectroscopy of ZrO2 zirconia
Publication TypePalaiseau Article
Acknowledgements

None

Author Address

Dash, LK (Reprint Author), Ecole Polytech, CEA, CNRS,UMR 7642, Solides Irradies Lab, F-91128 Palaiseau, France. Ecole Polytech, CEA, CNRS,UMR 7642, Solides Irradies Lab, F-91128 Palaiseau, France. CNRS, ENSEEG, LTPCM, F-38402 St Martin Dheres, France.

DOI10.1103/PhysRevB.70.245116
Dash, LK, Vast, N, Baranek, P, Cheynet, MC, Reining, L
Year of Publication2004
JournalPhys. Rev. B
Volume70
URLhttp://dx.doi.org/10.1103/PhysRevB.70.245116
Keywordspaper
Abstract

The atomic and electronic structures of zirconia are calculated within density functional theory, and their evolution is analyzed as the crystal-field symmetry changes from tetrahedral {[}cubic (c-ZrO2) and tetragonal (t-ZrO2) phases] to octahedral (hypothetical rutile ZrO2), to a mixing of these symmetries (monoclinic phase, m-ZrO2). We find that the theoretical bulk modulus in c-ZrO2 is 30% larger than the experimental value, showing that the introduction of yttria in zirconia has a significant effect. Electronic structure fingerprints which characterize each phase from their electronic spectra are identified. We have carried out electron energy-loss spectroscopy experiments at low momentum transfer and compared these results to the theoretical spectra calculated within the random phase approximation. We show a dependence of the valence and 4p (N-2,N-3 edge) plasmons on the crystal structure, the dependence of the latter being brought into the spectra by local-field effects. Last, we attribute low energy excitations observed in EELS of m-ZrO2 to defect states 2 eV above the top of the intrinsic valence band, and the EELS fundamental band gap value is reconciled with the 5.2 or 5.8 eV gaps determined by vacuum ultraviolet spectroscopy.

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