Ionic conductivity of directionally solidified zirconia-mullite eutectics
authors Carvalho, RG; Kovalevsky, AV; Lufaso, MW; Silva, RF; Costa, FM; Figueiredo, FM
nationality International
journal SOLID STATE IONICS
author keywords Zirconia; Mullite; Eutectics; Directional solidification; Ionic conductivity
keywords ELECTRICAL-CONDUCTIVITY; STABILIZED ZIRCONIA; PHYSICAL-PROPERTIES; COMPOSITES; MICROSTRUCTURE; OXIDE; DIFFRACTION; FIBERS; SINGLE
abstract The properties of directionally solidified eutectic (DSE) zirconia-mullite composites are presented. These materials combine two oxide ion conductors in eutectic microstructures stable over broad temperature (570-1415 degrees C) and PO2 (10(-20) to 10(5) Pa) ranges, which are pertinent for their application as high temperature (>1200 degrees C) solid electrolytes, e.g. in Nernstian sensors. X-ray diffraction and scanning electron microscopy/energy dispersive spectroscopy results reveal a composite structure comprising eutectic crystals of mullite and zirconia, and an intergranular amorphous phase rich in Al-Y-Si-O. The amorphous phase is crystallised upon annealing at 1400 degrees C, and the resulting composites have a composition close to the nominal eutectic consisting of 79 vol.% mullite and 21 vol.% zirconia. The electrical conductivity of these materials is rationalized in terms of percolation, fraction and properties of each phase, attaining values in excess of 0.01 S/cm at 1370 degrees C and displaying Arrhenius behaviour with activation energy of 70 kJ/mol. The broad electrolytic domain of these solid electrolytes is demonstrated by conductivity measurements carried out from 600 degrees C to 1370 degrees C in O2, air, Ar and 10%H-2 + 90%N-2 atmospheres. (C) 2013 Elsevier B.V. All rights reserved.
publisher ELSEVIER SCIENCE BV
issn 0167-2738
year published 2014
volume 256
beginning page 45
ending page 51
digital object identifier (doi) 10.1016/j.ssi.2013.12.033
web of science category Chemistry, Physical; Physics, Condensed Matter
subject category Chemistry; Physics
unique article identifier WOS:000332354100007
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