Issue 22, 2012

Surface proton conductivity of dense nanocrystalline YSZ

Abstract

Ionic transport in nanocrystalline solid oxides is of considerable current interest. Several studies have reported room-temperature proton conductivity in nanoscaled 8 mol% Y2O3-doped zirconia (YSZ), although the location of the transport species is not clear. In this study, nanocrystalline YSZ with a grain size of ∼50 nm was prepared by spark-plasma sintering of nanoscaled commercial powder to a density of >97% of the theoretical value. Impedance spectroscopy was employed to analyze the electrical behavior in the temperature range 25–600 °C in H2O- and D2O-wetted atmospheres (air, O2 and 10% H2 : 90% N2). Transport in wet conditions below 50 °C is limited to the sample surface and occurs via proton hopping (Grötthus mechanism), as demonstrated by a conductive H+/D+ isotope effect. The impedance in these conditions is dominated by a single arc which can be modelled with parallel paths for proton transport on the lateral sample surface and a capacitance with values of the order of those of the grain interior. Surface proton transport is considerable, exhibiting a resistance at 26 °C in wet atmospheres comparable to that obtained at ∼300 °C. In contrast, transport by volumetric processes (grain, grain boundary or nanopores) was demonstrated to be insignificant by experiments involving conductivity measurements with a coated lateral surface, with electrode configurations of different areas, and emf measurements in a water-vapour concentration cell.

Graphical abstract: Surface proton conductivity of dense nanocrystalline YSZ

Article information

Article type
Paper
Submitted
07 Mar 2012
Accepted
19 Apr 2012
First published
19 Apr 2012

J. Mater. Chem., 2012,22, 11208-11213

Surface proton conductivity of dense nanocrystalline YSZ

C. Tandé, D. Pérez-Coll and G. C. Mather, J. Mater. Chem., 2012, 22, 11208 DOI: 10.1039/C2JM31414B

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