Oxygen-Storage Materials BaYMn2O5+未 from the Quantum-Chemical Point of View

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• 作者：Michael Gille脽en ; Marck Lumeij ; Janine George ; Ralf Stoffel ; Teruki Motohashi ; Shinichi Kikkawa ; Richard Dronskowski
• 刊名：Chemistry of Materials
• 出版年：2012
• 出版时间：May 22, 2012
• 年：2012
• 卷：24
• 期：10
• 页码：1910-1916
• 全文大小：309K
• 年卷期：v.24,no.10(May 22, 2012)
• ISSN：1520-5002

文摘

The experimentally known perovskite-like materials BaYMn₂O_5+未 (未 = 0, 0.5, 1) are characterized by a remarkably reversible oxygen-storage capacity at a moderate 500 掳C. We try to elucidate the local structures of the vacancy arrangements in these compounds taking place after an oxygen release. This is done for the three compounds with the help of both ab initio total-energy calculations of density-functional quality and using classical structure rationale. Our results are compared with experimental structure findings. We further calculate oxygen-vacancy formation energies and predict the pathways of the oxygen atoms through the crystal by using NEB (nudged elastic band) calculations. Structure diagrams of the most likely energy pathways for oxygen migration are presented. Finally, thermodynamic considerations of the oxygen intake are carried out based on quasiharmonic phonon calculations and compared with experimental data. The theoretical molar reaction enthalpy for oxidizing BaYMn₂O₅ to BaYMn₂O₆ matches the experimental value.

Keywords:

oxygen-storage material; nudged elastic band; DFT; oxygen hopping pathways; ab initio thermochemistry; BaYMn₂O₆