Oxygen diffusion mechanism in the mixed ion-electron conductor NdBaCo2O5+x

被引:41
作者
Hu, Y. [2 ]
Hernandez, O. [1 ]
Broux, T. [1 ]
Bahout, M. [1 ]
Hermet, J. [3 ]
Ottochian, A. [2 ]
Ritter, C. [4 ]
Geneste, G. [3 ]
Dezanneau, G. [2 ]
机构
[1] Univ Rennes 1, Inst Sci Chim Rennes, Equipe Chim Solide & Mat, CNRS,UMR 6226, F-35042 Rennes, France
[2] Ecole Cent Paris, SPMS Lab, F-92295 Chatenay Malabry, France
[3] CEA, DAM, DIF, F-91297 Arpajon, France
[4] Inst Max Von Laue Paul Langevin, F-38042 Grenoble 9, France
关键词
MAXIMUM-ENTROPY METHOD; SOLID OXIDE FUEL; 3-DIMENSIONAL VISUALIZATION; MOLECULAR-DYNAMICS; PEROVSKITES; CATHODE;
D O I
10.1039/c2jm34396g
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Double perovskite cobaltites were recently presented as promising cathode materials for solid oxide fuel cells. While an atomistic mechanism was proposed for oxygen diffusion in this family of materials, no direct experimental proof has been presented so far. We report here the first study that directly compares experimental and theoretical diffusion pathways of oxygen in an oxide, namely in the double cobaltite compound, NdBaCo2O5+x. Model-free experimental nuclear density maps are obtained from the maximum entropy method combined with Rietveld refinement against high resolution neutron diffraction data collected at 1173 K. They are then compared to theoretical maps resulting from classical molecular dynamics calculations. The analysis of 3D maps of atomic densities allows identifying unambiguously the pathways and the mechanisms involved in the oxide ion diffusion. It is shown that oxygen diffusion occurs along a complex trajectory between Nd- and Co-containing a,b planes. The study also reveals that Ba-containing planes act as a barrier for oxygen diffusion. The diffusion mechanism is also supported through the oxygen sites occupancy analysis that confirms the increase of oxygen vacancies in the cobalt-planes on heating. The use of such combined experimental and theoretical analysis should be considered as a very powerful approach for materials design.
引用
收藏
页码:18744 / 18747
页数:4
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