Paramagnetic Defects in Polycrystalline Zirconia: An EPR and DFT Study

By C. Gionco, M. Paganini, E. Giamello, R. Burgess, C. D. Valentin, Gianfranco Pacchioni. 2013

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The paramagnetic defects present in pristine zirconium dioxide (ZrO2) and those formed upon reductive treatments (either annealing or UV irradiation in H2) are described and rationalized by the joint use of electron paramagnetic resonance (EPR) and DFT supercell calculations. Three types of Zr3+ reduced sites have been examined both in the bulk of the solid (one center) and at the surface (two centers). Trapping electron centers different from reduced Zr ions are also present, whose concentration increases upon annealing. A fraction of these sites are paramagnetic showing a symmetric signal at g = 2.0023, but the majority of them are EPR silent and are revealed by analysis of electron transfer from the reduced solid to oxygen. The presence of classic F-type centers (electrons in bulk oxygen vacancies) is disregarded on the basis of the g-tensor symmetry. This is expected, on the basis of theoretical calculations, to be anisotropic and thus incompatible with the observed signal. In general terms, ZrO2 has ...

Subfields: Inorganic Chemistry, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/e9166168e5fb45767c40b80205dd4089df5036f5