Issue 33, 2011
From the journal:

Physical Chemistry Chemical Physics

Defect processes in orthorhombic LnBaCo2O5.5 double perovskites

I. D. Seymour,a   A. Chroneos,*b   J. A. Kilner*a  and  R. W. Grimes*a  

* Corresponding authors

a Department of Materials, Imperial College London, London SW7 2AZ, United Kingdom
E-mail: j.kilner@imperial.ac.uk, r.grimes@imperial.ac.uk

b Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ, United Kingdom
E-mail: alexander.chroneos@imperial.ac.uk

Abstract

Static atomistic simulations based on the Born model were used to investigate intrinsic defect processes in orthorhombic LnBaCo2O5.5 (Ln = Y, La, Pr, Nd, Sm, Gd, Dy, Ho, Er, and Yb) double perovskites. It was found that Ln/Ba antisite disorder is the lowest energy defect reaction, with the large Ln cations giving rise to smaller antisite energies. On the oxygen sublattice the oxygen Frenkel disorder dominates and also decreases in energy with increasing Ln cation size. The lowest energy oxygen vacancy and interstitial positions are in the LnO0.5 and CoO2 layers respectively. Interestingly, the calculations indicate that oxygen vacancies cluster with Ba antisite defects (occupying Ln sites). This suggests that the transport of oxygen vacancies will be influenced not only by the oxygen Frenkel energy but also the antisite energy. We propose that PrBaCo2O5.5 most efficiently balances these two competing effects as it has an oxygen Frenkel energy of just 0.24 eV per defect combined with a high antisite energy (0.94 eV), which ensures that the A cation sublattice will remain more ordered.

Graphical abstract: Defect processes in orthorhombic LnBaCo2O5.5 double perovskites

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Article information

DOI
https://doi.org/10.1039/C1CP21471C
Article type
Paper
Submitted
07 May 2011
Accepted
28 Jun 2011
First published
18 Jul 2011

Phys. Chem. Chem. Phys., 2011,13, 15305-15310

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Defect processes in orthorhombic LnBaCo2O5.5 double perovskites

I. D. Seymour, A. Chroneos, J. A. Kilner and R. W. Grimes, Phys. Chem. Chem. Phys., 2011, 13, 15305 DOI: 10.1039/C1CP21471C

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