Position preference and diffusion path of an oxygen ion in apatite-type lanthanum silicate La 9.33Si 6O 26: A density functional study

Liao, Ting, Sasaki, Taizo, Suehara, Shigeru and Sun, Zigi (2011) Position preference and diffusion path of an oxygen ion in apatite-type lanthanum silicate La 9.33Si 6O 26: A density functional study. Journal of Materials Chemistry, 21 9: 3234-3242. doi:10.1039/c0jm02473b


Author Liao, Ting
Sasaki, Taizo
Suehara, Shigeru
Sun, Zigi
Title Position preference and diffusion path of an oxygen ion in apatite-type lanthanum silicate La 9.33Si 6O 26: A density functional study
Journal name Journal of Materials Chemistry   Check publisher's open access policy
ISSN 0959-9428
1364-5501
Publication date 2011-03-07
Sub-type Article (original research)
DOI 10.1039/c0jm02473b
Open Access Status Not Open Access
Volume 21
Issue 9
Start page 3234
End page 3242
Total pages 9
Place of publication Cambridge, United Kingdom
Publisher Royal Society of Chemistry
Subject 2505 Materials Chemistry
1600 Chemistry
Abstract Using density functional theory, we investigated the position preference and diffusion mechanisms of interstitial oxygen ions in lanthanum silicate La 9.33Si 6O 26, which is an apatite-structured oxide and a promising candidate electrolyte material for solid oxide fuel cells. The reported lanthanum vacancies were explicitly taken into account by theoretically determining their arrangement with a supercell model. The most stable structures and the formation energies of oxygen interstitials were determined for each charged state. It was found that the double-negatively charged state is stable over a wide range of the Fermi level, and that the excess oxygen ions form split interstitials with the original oxygen ions, while the neutral and the single-negatively charged states preferably form molecular oxygen. These species were found near the lanthanum vacancy site. The theoretically determined migration pathway along the c-axis essentially follows an interstitialcy mechanism. The obtained migration barrier is sensitive to the charge state, and is also affected by the lanthanum vacancy. The barrier height of the double-negatively charged state was calculated to be 0.58 eV for the model structure, which is consistent with the measured activation energy.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Australian Institute for Bioengineering and Nanotechnology Publications
 
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