Crystal structure of compositionally homogeneous ZrO2-Sc2O3 nanopowers synthesized by gel-combustion

P.M. ABDALA; D.G. LAMAS; M.E. FERNÁNDEZ DE RAPP; N.E. WALSÖE DE RECA; A.F. CRAIEVICH

2006 Activity Report of the Brazilian Synchrotron Light Laboratory

Laboratorio Nacional de Luz Sincrotrón (LNLS)

Año: 2007 p. 916 - 916

1518-0204

ZrO2-Sc2O3 ceramics have great technological interest because they exhibit very high ionic conductivity and, therefore, can be used as solid electrolytes in intermediate-temperaturesolid-oxide fuel cells. 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 (8c sites of the Fm3m space group). If the dopant content is further increased, the cubic phase is retained. For ZrO2-Sc2O3 solid solutions, a beta-phase with rhombohedral structure has been reported.In this work, the crystal structure of nanocrystalline ZrO2-Sc2O3 solid solutions was investigated by means of synchrotron radiation X-ray powder diffraction (SR-XPD). Thesematerials were synthesized by a novel gel-combustion route.