EXAFS study of nanostructured ZrO2-Y2O3 solid solutions

I.O. FÁBREGAS; R.O. FUENTES; D.G. LAMAS; M.E. FERNÁNDEZ DE RAPP; N.E. WALSÖE DE RECA; M.C.A. FANTINI; A.F. CRAIEVICH

Activity Report of the Brazilian Synchrotron Light Laboratory

Año: 2005 p. 496 - 497

Compositionally homogeneous zirconia-based solid solutions exhibit three tetragonal forms, all belonging to the P42/nmc space group. The stable tetragonal form is called the t-form, which is restricted to the solubility limit predicted by the equilibrium phase diagram. There is also a t'-form with a wider solubility, but unstable in comparison with the mixture of the t-form and cubic phase. Finally, the t"-form has an axial ratio c/a of unity, but with the oxygen atoms displaced along the c axis from their ideal sites of the cubic phase.   The local structure of nanocrystalline ZrO2-based solid solutions exhibiting the metastable forms of the tetragonalphase has not been extensively studied yet. The most complete works deals with nanostructured ZrO2-CeO2 solid solutions, while there are only a few studies on ZrO2-Y2O3 nanopowders.   In this work, we present an EXAFS study of compositionally homogeneous ZrO2-Y2O3 nanopowders for compositions close to the tetragonal/cubic boundary, (11.0 ± 0.5) mol% Y2O3 (determined in a previous synchrotron XRD study). A t-form powder, with low Y2O3 content, was also analyzed for purpose of comparison.