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Issue 22, 2018
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The blocking effect of surface dislocations on oxygen tracer diffusion in SrTiO3

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Abstract

The existence of a polishing-induced damaged zone at the surface of standard, nominally undoped, single-crystal SrTiO3 is exploited in diffusion studies in order to investigate the interaction between oxygen vacancies and dislocations. Tracer diffusion profiles for such crystals are proposed to exhibit three features: a short feature arising from a surface space-charge layer; an intermediate, longer feature arising from the high density of dislocations in the damaged zone; and finally, a much longer feature corresponding to diffusion in the homogeneous bulk crystal. Quantitative information is provided by finite-element-method calculations. First, the distribution of oxygen vacancies in a sample in which space-charge zones depleted of oxygen vacancies form at dislocations and at the sample surface is calculated; subsequently, oxygen tracer diffusion profiles for such vacancy distributions are simulated. The proposed model is experimentally validated by performing conventional oxygen isotope exchange and depth-profiling experiments on commercial single-crystal SrTiO3. In this way, we confirm directly that arrays of dislocations in acceptor-doped SrTiO3, by virtue of the attendant space-charge tubes, hinder the diffusion of oxygen. Finally, in order to aid the prediction of oxygen tracer diffusion profiles in polished perovskite single-crystal substrates, we suggest a one-dimensional continuum approach that takes account of the complex, three-dimensional diffusion problem posed by dislocation arrays with depletion space-charge tubes.

Graphical abstract: The blocking effect of surface dislocations on oxygen tracer diffusion in SrTiO3

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Publication details

The article was received on 06 Apr 2018, accepted on 18 May 2018 and first published on 18 May 2018


Article type: Paper
DOI: 10.1039/C8CP02191K
Citation: Phys. Chem. Chem. Phys., 2018,20, 15455-15463
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    The blocking effect of surface dislocations on oxygen tracer diffusion in SrTiO3

    H. Schraknepper, T. E. Weirich and R. A. De Souza, Phys. Chem. Chem. Phys., 2018, 20, 15455
    DOI: 10.1039/C8CP02191K

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