de Laune, Benjamin P., Rees, Gregory J., Whitaker, Mariana J., Hah, Hien-Yoong, Johnson, Charles E., Johnson, Jacqueline A., Brown, Dennis E., Tucker, Matthew G., Hansen, Thomas C., Berry, Frank J., Hanna, John V. and Greaves, Colin (2017) Oxygen insertion reactions within the one-dimensional channels of phases related to FeSb2O4. Inorganic Chemistry, 56 (1). pp. 594-607. doi:10.1021/acs.inorgchem.6b02466

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Abstract

The structure of the mineral schafarzikite, FeSb2O4, has one-dimensional channels with walls comprising Sb3+ cations; the channels are separated by edge-linked FeO6 octahedra that form infinite chains parallel to the channels. Although this structure provides interest with respect to the magnetic and electrical properties associated with the chains and the possibility of chemistry that could occur within the channels, materials in this structural class have received very little attention. Here we show, for the first time, that heating selected phases in oxygen-rich atmospheres can result in relatively large oxygen uptakes (up to ∼2% by mass) at low temperatures (ca. 350 °C) while retaining the parent structure. Using a variety of structural and spectroscopic techniques, it is shown that oxygen is inserted into the channels to provide a structure with the potential to show high one-dimensional oxide ion conductivity. This is the first report of oxygen-excess phases derived from this structure. The oxygen insertion is accompanied not only by oxidation of Fe2+ to Fe3+ within the octahedral chains but also Sb3+ to Sb5+ in the channel walls. The formation of a defect cluster comprising one 5-coordinate Sb5+ ion (which is very rare in an oxide environment), two interstitial O2– ions, and two 4-coordinate Sb3+ ions is suggested and is consistent with all experimental observations. To the best of our knowledge, this is the first example of an oxidation process where the local energetics of the product dictate that simultaneous oxidation of two different cations must occur. This reaction, together with a wide range of cation substitutions that are possible on the transition metal sites, presents opportunities to explore the schafarzikite structure more extensively for a range of catalytic and electrocatalytic applications.

Item Type:	Journal Article
Subjects:	Q Science > QD Chemistry Q Science > QE Geology
Divisions:	Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	Minerals -- Oxidation , Mineralogy, Catalysis, Electrocatalysis
Journal or Publication Title:	Inorganic Chemistry
Publisher:	American Chemical Society
ISSN:	0020-1669
Official Date:	3 January 2017
Dates:	Date Event 3 January 2017 Published 15 December 2016 Accepted 12 October 2016 Submitted
Volume:	56
Number:	1
Page Range:	pp. 594-607
DOI:	10.1021/acs.inorgchem.6b02466
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	Engineering and Physical Sciences Research Council (EPSRC), European Union (EU), Birmingham Science City, Advantage West Midlands (AWM), European Regional Development Fund (ERDF), University of Warwick, Biotechnology and Biological Sciences Research Council (Great Britain) (BBSRC)
Grant number:	EP/L014114/1 (EPSRC)

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