Metastable forms of the tetragonal phase in compositionally homogeneous, nanocrystalline zirconia-ceria powders synthesised by gel-combustion

DIEGO G. LAMAS; GUSTAVO E. LASCALEA; RICARDO E. JUÁREZ; ELISABETH DJURADO; LIDIA PÉREZ; NOEMÍ E. WALSÖE DE RECA

JOURNAL OF MATERIALS CHEMISTRY

The Royal Society of Chemistry Publishing

Año: 2003 vol. 13 p. 904 - 910

0959-9428

The crystal structure of compositionally homogeneous, nanocrystalline ZrO2–10, 30, 50, 70 and 90 mol% CeO2 powders synthesised by a pH-controlled nitrate-glycine gel-combustion process has been studied by X-ray diffraction and Raman spectroscopy. All the powders with a CeO2 content up to 70 mol% exhibited the tetragonal phase (P42/nmc space group), whereas the ZrO2-90 mol% CeO2 solid solution presented the cubic phase (Fm3m space group). The axial ratio c/a decreased with increasing CeO2 content and became unity for ZrO2-70 mol% CeO2 powders. By analysing X-ray diffraction data using the Rietveld method, it was foundthat this material exhibited the t"-form of the tetragonal phase (the oxygen atoms were displaced from their ideal sites of the cubic phase along the c axis). Raman spectroscopy study confirmed the results found by X-ray diffraction. The morphology of the nanopowders was also evaluated.