EXAFS study of compositionally homogeneous ZrO2-CaO nanopowers

FÁBREGAS, I.O.; LAMAS, D.G.; ACUÑA, L.M.; FUENTES, R.O.; FERNÁNDEZ DE RAPP, M.E.; WALSOE DE RECA, N.E.; FANTINI, M.C.A; CRAIEVICH A.F.; PRADO, R.J.

Activity Report of the Brazilian Synchrotron Light Laboratory

Año: 2006 p. 705 - 706

   Compositionally homogeneous ZrO2-based solid solutions exhibit three tetragonal forms, all belonging to the P42/nmc space group. The stable tetragonal form is called the cation 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 tetragonal phase has not been extensively studied yet. The most complete works deals with nanostructured ZrO2-CeO2 and ZrO2-Y2O3 solid solutions, while no studies have been reported on the ZrO2-CaO system.   In this work, we studied the Zr-O bond in compositionally homogeneous ZrO2-CaO nanopowders with CaO contents up to 20 mol%, exhibiting the metastable forms of the tetragonal phase or the cubic one depending on the composition.