Soft X-ray absorption spectroscopy study of (Ba0.5Sr0.5) (Co0.8Fe0.2)1-xNbxO3-δ with different content of Nb (5%-20%)

JOURNAL OF ALLOYS AND COMPOUNDS

卷:650

Article

Egorova, Y. V.¹  Scherb, T.²  Schumacher, G.²  Bouwmeester, H. J. M.³  Filatova, E. O.¹ 

[1] St Petersburg State Univ, Inst Phys, St Petersburg 198504, Russia

[2] Helmholtz Zentrum Berlin Mat & Energie GmbH, D-14109 Berlin, Germany

[3] Univ Twente, NL-7500 AE Enschede, Netherlands

关键词: Solid oxide fuel cell;    Microstructure;    Local bonding environment;    Near edge X-ray absorption fine structure;   

DOI  :  10.1016/j.jallcom.2015.08.073

来源: Elsevier

【 摘 要 】

The mixed electronic ionic conducting materials (Ba0.5Sr0.5) (Co0.8Fe0.2)(1-x)NbxO3-delta with partial Nb substitution (x: 0.05, 0.10, 0.15, 0.20) for B cations (Co/Fe), synthesized using a solid state reaction method, have been studied by near edge X-ray absorption fine structure (NEXAFS). Co L-2,L-3- absorption spectra of (Ba0.5Sr0.5) (Co0.8Fe0.2)(1-x)NbxO3-delta (BSCFN) powders were analyzed with the purpose to understand the influence of the Nb substitution on the atomic electronic structure of BSCFN. The joint analysis of the Co L-2,3(-) absorption spectra reveals the presence of mixed oxidation states Co2+/Co3+ in all the studied BSCFN structures. It was established that the proportion of oxidation states Co2+/Co3+ and the corresponding coordinations of Co atoms depend on the content of Nb. In the 10% Nb substituted BSCF sample Co atoms mostly occur in the Co2+ oxidation state and are preferentially characterized by an octahedral coordination site. In all other structures Co atoms are rather characterized by Co2+/Co3+ oxidation states and occupy both octahedrally and tetrahedrally coordinated sites. (C) 2015 Elsevier B.V. All rights reserved.

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