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Defect processes in orthorhombic LnBaCo2O5.5 double perovskites

Seymour, I. D.; Chroneos, A.; Kilner, J. A. and Grimes, R. W. (2011). Defect processes in orthorhombic LnBaCo2O5.5 double perovskites. Physical Chemistry Chemical Physics, 13(33) pp. 15305–15310.

DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1039/c1cp21471c
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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.

Item Type: Journal Article
Copyright Holders: 2011 the Owner Societies
ISSN: 1463-9084
Academic Unit/Department: Mathematics, Computing and Technology > Engineering & Innovation
Item ID: 35210
Depositing User: Alexander Chroneos
Date Deposited: 08 Nov 2012 14:56
Last Modified: 08 Nov 2012 14:56
URI: http://oro.open.ac.uk/id/eprint/35210
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