The systems Zr(Nb,Ti)(R)O2-delta, R = Yb, Ca - optimization of mixed conductivity and comparison with results of other systems (R = Y and Gd)

resumo

In this work we address the optimization of mixed conductivity in fluorite compounds based on zirconia. Phase relations of the new systems YbO1.5-NbO2.5-ZrO2, and CaO-NbO2.5-ZrO2 are presented: The limit of the cubic defect fluorite phase in YbO1.5-NbO2.5-ZrO2 closely resembles that of the system YO1.5-NbO2.5-ZrO2, whilst in CaO-NbO2.5-ZrO2 is narrow extending to include composition Ca0.255Nb0.15Zr0.595O1.82 at 1500 degreesC. The influence of dopant ion size, charge and composition on ionic conduction is assessed and parallels are drawn with the systems YO1.5-NbO2.5-ZrO2 and YO1.5-TiO2-ZrO2. Comparison of these results with published data on the Ti containing systems CaO-TiO2-ZrO2, GdO1.5-TiO2-ZrO2 shows that the highest mixed conducting compositions can only be offered in the system YO1.5-TiO2-ZrO2 out of all the systems here studied. (C) 2003 Elsevier Science (USA). All rights reserved.

palavras-chave

PHASE-RELATIONS; ELECTRICAL-CONDUCTIVITY; SOLID-SOLUTIONS; 1500-DEGREES-C; OXIDE; MICROSTRUCTURE; ZRO2-Y2O3-TIO2; DIFFRACTION; EQUILIBRIA

categoria

Chemistry

autores

Fagg, DP; Feighery, AJ; Irvine, JTS

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