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Issue 17, 2008
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Using 18O/16O exchange to probe an equilibrium space-charge layer at the surface of a crystalline oxide: method and application

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Abstract

The use of an 18O/16O exchange experiment as a means for probing surface space-charge layers in oxides is examined theoretically and experimentally. On the basis of a theoretical treatment, isotope penetration profiles are calculated for 18O/16O exchange across a gas–solid interface and subsequent diffusion of the labelled isotope through an equilibrium space-charge layer depleted of mobile oxygen vacancies and into a homogeneous bulk phase. Profiles calculated for a range of conditions all have a characteristic shape: a sharp drop in isotope fraction close to the surface followed by a normal bulk diffusion profile. Experimental 18O profiles in an exchanged (001) oriented single crystal of Fe-doped SrTiO3 were measured by time-of-flight secondary ion mass spectrometry (ToF-SIMS). By extracting the space-charge potential from such profiles, we demonstrate that this method allows the spatially resolved characterization of space-charge layers at the surfaces of crystalline oxides under thermodynamically well-defined conditions.

Graphical abstract: Using 18O/16O exchange to probe an equilibrium space-charge layer at the surface of a crystalline oxide: method and application

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Article information


Submitted
19 Dec 2007
Accepted
07 Feb 2008
First published
04 Mar 2008

Phys. Chem. Chem. Phys., 2008,10, 2356-2367
Article type
Paper

Using 18O/16O exchange to probe an equilibrium space-charge layer at the surface of a crystalline oxide: method and application

R. A. De Souza and M. Martin, Phys. Chem. Chem. Phys., 2008, 10, 2356
DOI: 10.1039/B719618K

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