Synchrotron XRD study of ZrO2-CeO2 nanopowders synthesised by gel-combustion

D.G. LAMAS; R.O. FUENTES; I.O. FÁBREGAS; M.E. RAPP; G.E. LASCALEA; J.R. CASANOVA; N.E. WALSÖE DE RECA; A.F. CRAIEVICH.

Florencia - Italia

Congreso; Congress of the International Union of Crystallography; 2005

In this work, the crystal structure of nanocrystalline ZrO2-CeO2 solid solutions, synthesised by a pH-controlled nitrate-glycine gel-combustion process, has been studied. By using a high-intensity synchrotron X-ray diffractometer (XRD-1 beamline of the LNLS, Brazilian Light Facility), small peaks of the tetragonal phase, which correspond to forbidden reflections in the case of a perfect cubic fluorite structure, were detected. By monitoring the most intense of these reflections, (112), as a function of the CeO2 content, the tetragonal-cubic phase compositional boundary was found to be at (85±5) mol% CeO2. For a CeO2 content up to (68±2) mol%, a tetragonal phase with c/a > 1 was detected, whereas, between 68 and 85 mol% CeO2, the existence of a tetragonal phase with c/a = 1 and oxygen anions displaced from their ideal positions in the cubic phase (keeping the tetragonal symmetry) was verified. Finally, solid solutions with higher CeO2 contents exhibit the cubic fluorite-type phase.