Reversible Topochemical Exsolution of Iron in BaFe2+2(PO4)21. Issue 49 (24th October 2014)

• Record Type: Journal Article
• Authors: David, Rénald; Kabbour, Houria; Filimonov, Dmitry; Huvé, Marielle; Pautrat, Alain; Mentré, Olivier
• Is Part Of: Angewandte Chemie international edition. Volume 53:Issue 49(2014)
• Page Start: 13365
• Page End: 13370
• Publication Date: 2014-10-24
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201404476
• Languages: English
• ISSNs: 1433-7851

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>BaFe²⁺₂(PO₄)₂ was recently prepared and identified as the first 2D‐Ising ferromagnetic oxide with an original reentrant structural transition driven by high‐spin Fe²⁺ ions arranged in honeycomb layers. Both long‐term air exposure and moderate temperature (<italic>T</italic>&gt;375 °C) leads to topochemical oxidation into iron‐depleted compounds with mixed Fe²⁺/Fe³⁺ valence. This process is unique, as the exsolution is effective even from single crystal with preservation of the initial crystallinity, and the structure of the deficient BaFe_{2−<italic>x</italic>}(PO₄)₂ (<italic>x</italic>&lt;ca. 0.5) is fully ordered for <italic>x</italic>=2/7 and 1/3 with creation of novel original depleted triangular lattices. Under flowing H₂/Ar, Fe is reincorporated in the structure above 480 °C, as reproduced under the electron beam in a transmission microscope. After Fe exsolution, the insulating ferromagnetic compound turns into an antiferromagnetic semiconductor.</p> </abstract>