Abstract—

A study of mixed systems based on zirconium oxide is carried out using X-ray absorption fine structure (XAFS: XANES, EXAFS) spectrocscopy. New reliable information concerning zirconium and yttrium on the state of Zr—Y and Zr–Y–Mg samples, parameters of the local atomic structure, interatomic distances, and coordination numbers is obtained; the possible variants of structural models are considered. An analysis of the XAFS data based on the pyrochlore and fluorite models and taking into account the abnormally low coordination numbers for zirconium and the shortening of the Zr–O bond lengths (in comparison with bulk reference points) unambiguously indicates the formation of a number of oxygen vacancies. The disordering of both sublattices (due to structural distortions of the zirconium lattice) increases in the series of samples Zr—Y and Zr–Y–Mg. With respect to yttrium, in the studied samples, the formation of both a distorted ZrY_zO_x fluorite nanophase (partially amorphized) with significant defects in the anion and cation sublattices, and a large amount of a distorted yttrium-oxide phase (nanophase, nanoclusters) is possible. It should also be noted that the state and local environment of yttrium is more stable than that of zirconium. The data obtained using X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy are in good agreement with each other.