Metastable Phase Diagram of Nanocrystalline ZrO(2)-Sc(2)O(3) Solid Solutions

We have investigated the crystal structures and phase transitions of nanocrystalline ZrO(2)-1 to -13 mol % Sc(2)O(3) by synchrotron X-ray powder diffraction and Raman spectroscopy. ZrO(2)-Sc(2)O(3) nanopowders were synthesized by using a stoichiometric nitrate-lysine get-combustion route. Calcination processes at 650 and at 850 degrees C yielded nanocrystalline materials with average crystallite sizes of (10 +/- 1) and (25 +/- 2) nm, respectively. Only metastable tetragonal forms and the cubic phase were identified, whereas the stable monoclinic and rhombohedral phases were not detected in the compositional range analyzed in this work. Differently from the results of investigations reported in the literature for ZrO(2)-Sc(2)O(3) materials with large crystallite sizes, this study demonstrates that, if the crystallite sizes are small enough (in the nanometric range), the metastable t ``-form of the tetragonal phase is retained. We have also determined the t`-t `` and t ``-cubic compositional boundaries at room temperature and analyzed these transitions at high temperature. Finally, using these results, we built up a metastable phase diagram for nanocrystalline compositionally homogeneous ZrO(2)-Sc(2)O(3) solid solutions that strongly differs from that previously determined from compositionally homogeneous ZrO(2)-Sc(2)O(3), Solid solutions with much larger crystallite sizes.

Brazilian Synchrotron Light Laboratory (LNLS)

Brazilian Synchrotron Light Laboratory (LNLS)

CNPq-CONICET

Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina (CONICET)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

SECyT (Argentina)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

CAPES-SECyT (Brazil-Argentina)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

CNPq (Brazil)[490289/2005-3]

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

CNPq (Brazil)[490580/2008-4]

ANPCyT Agencia Nacional de Promocion Cientifica y Tecnologica[14268]

Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT)

ANPCyT Agencia Nacional de Promocion Cientifica y Tecnologica[38309]

Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT)

Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT)

ANPCyT Agencia Nacional de Promocion Cientifica y Tecnologica[01152]

Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina (CONICET)

CONICET[6559]

Latin-American Centre for Physics (CLAF)

Latin-American Centre for Physics (CLAF)

Fundacion YPF

Fundacion YPF

[D10B-XPD-5364]

[6723]

[7296]