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Space–charge theory applied to the grain boundary impedance of proton conducting BaZr0.9Y0.1O3−δ

Kjølseth, Christian and Fjeld, Harald and Prytz, Øystein and Inge Dahl, Paul and Estournès, Claude and Haugsrud, Reidar and Norby, Truls Space–charge theory applied to the grain boundary impedance of proton conducting BaZr0.9Y0.1O3−δ. (2010) Solid State Ionics, vol. 181 (n° 5-7). pp. 268-275. ISSN 0167-2738

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Official URL: http://dx.doi.org/10.1016/j.ssi.2010.01.014

Abstract

The specific grain interior and grain boundary conductivities, obtained from impedance spectroscopy and the brick layer model, are reported for BaZr0.9Y0.1O3−δ as a function of pO2 and temperature. pO2-dependencies were indicative of dominating ionic and p-type electronic conduction for the grain interior under reducing and oxidizing conditions, respectively, while the grain boundaries showed an additional n-type electronic contribution under reducing conditions. Transmission electron microscopy revealed enrichment of Y in the grain boundary region. These findings indicate the existence of space–charge layers in the grain boundaries. A grain boundary core–space–charge layer model is therefore applied to interpret the data. Using a Mott– Schottky approximation, a Schottky barrier height of 0.5–0.6 V and an effective grain boundary width of 8– 10 nm (=2× space–charge layer thickness) is obtained at 250 °C in wet oxygen. Finite-element modelling of the complex impedance over a grain boundary with a space–charge layer depletion of protons yields a distorted semicircle as observed in the impedance spectra.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at Solid State Ionics website : http://www.sciencedirect.com/science/journal/01672738
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Other partners > Norwegian University of Science and Technology - NTNU (NORWAY)
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
Other partners > University of Oslo (NORWAY)
Laboratory name:
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Deposited By:Nihad Lahdifi

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