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Issue 9, 2013
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Visualizing oxygen anion transport pathways in NdBaCo2O5+δ by in situneutron diffraction

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Abstract

The layered perovskite NdBaCo2O5+δ (NBCO) was characterized using neutron powder diffraction under in situ conditions from 577–852 °C and in 10−1 to 10−4 atm oxygen. The best fit to the data was obtained in the tetragonal (P4/mmm) space group. No oxygen atom vacancy ordering was observed that warranted a lowering of the symmetry to orthorhombic (Pmmm). Two P4/mmm structural models were investigated: Model 1 (no split sites) and Model 2 (split Nd and O2 sites). Transport of oxygen through the material via the vacancy hopping mechanism likely involves the nearest-neighbor oxygen atom sites in the Nd layer. Total oxygen stoichiometry values were in the range 5.51 ≤ δ ≤ 5.11. The tetragonal lattice parameters increased with temperature as expected. However, the a-axis expands while the c-axis contracts with decreasing pO2 at a given temperature due to increasing vacancy concentration in the Nd layer.

Graphical abstract: Visualizing oxygen anion transport pathways in NdBaCo2O5+δ by in situ neutron diffraction

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Article information


Submitted
29 Nov 2012
Accepted
07 Jan 2013
First published
14 Jan 2013

J. Mater. Chem. A, 2013,1, 3091-3100
Article type
Paper

Visualizing oxygen anion transport pathways in NdBaCo2O5+δ by in situ neutron diffraction

R. A. Cox-Galhotra, A. Huq, J. P. Hodges, J. Kim, C. Yu, X. Wang, A. J. Jacobson and S. McIntosh, J. Mater. Chem. A, 2013, 1, 3091
DOI: 10.1039/C3TA01308A

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