Influence of crystallite size on the tetragonal-cubic phase transition in nanocrystalline Zr0.5Ce0.5O2 solid solutions: A study by high-temperature XRD

ACUÑA, L. M.; LAMAS, D. G.; FUENTES, R. O.; CRAIEVICH, A. F.

Campinas

Encuentro; RAU 18; 2008

LNLS-CNPEM

The aim of this work is tostudy the effect of crystallite size on the tetragonal-cubic phase transitionas function of temperature on nanocrystalline powders of ZrO2-50 mol% CeO2 by high-temperature X-raydiffraction (HT-XRD) employing synchrotron radiation. Powders were synthesizedby the gelcombustion method and citratecomplexation method with an average crystallite size about 30 nm and 8 nm,respectively. The evolution of the (112) peak with temperature was studied inall systems. The (112) peak is a characteristic reflection of t00-form (pseudo-fluorite), whileit is a forbbiden reflection in a fluorite-like structure of the cubic phase.This reflection is related to the displacement of the oxygen anions. Bymonitoring of this peak it was possible to discriminate between tetragonal andcubic phases. The fractional z-coordinate of the oxygen atom in the asymmetricunit, z(O), can be determined from the measured integrated intensities, I(112)and I(111)