Size-dependent phase transitions in nanostructured zirconia-scandia solid solutions

The dependences of phase stability and solid state phase transitions on the crystallite size in ZrO2-10, 12 and 14 mol% Sc2O3 nanopowders are investigated by X-ray powder diffraction using a synchrotron source (S-XPD). The average crystallite sizes lie within the range of 35 to 100 nm, approximately. At room temperature these solid solutions were previously characterised as mixtures of a cubic phase and one or two rhombohedral phases, beta and gamma, with their fractions depending on composition and average crystallite sizes. In this study, it is shown that at high temperatures these solid solutions become cubic single-phased. The size-dependent temperatures of the transitions from the rhombohedral phases to the cubic phase at high temperature are determined through the analyses of a number of S-XPD patterns. These transitions were studied on cooling and on heating, exhibiting hysteresis effects whose relevant features are size and composition dependent.

Brazilian Synchrotron Light Laboratory (LNLS, Brazil)

Brazilian Synchrotron Light Laboratory (LNLS, Brazil) [D10B-XPD-7296, 9195]

CNPq (Brazil) [490289/2005-3, 490580/2008-4]

CNPq (Brazil)

Agencia Nacional de Promocion Cientifica y Tecnologica (Argentina)

Agencia Nacional de Promocion Cientifica y Tecnologica (Argentina) [38309, 01152, 02288]

CONICET (Argentina)

CONICET (Argentina) [6559]

FAPESP (Brazil)

FAPESP (Brazil)

LatinAmerican Centre for Physics

Latin-American Centre for Physics