Synthesis and magnetic characterisation of Fe1−xMgxSb2O4 (x = 0.25, 0.50, 0.75) and their oxygen-excess derivatives, Fe1−xMgxSb2O4+y. Issue 20 (15th May 2017)

• Record Type: Journal Article
• Authors: de Laune, Benjamin P.; Whitaker, Mariana J.; Marco, Jose F.; Thomas, Michael F.; Berry, Frank J.; Lees, Martin R.; Greaves, Colin
• Is Part Of: Journal of materials chemistry. Volume 5:Issue 20(2017)
• Page Start: 4985
• Page End: 4995
• Publication Date: 2017-05-15
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c7tc01256j
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : The structures and magnetic properties of Fe1− x Mg x Sb2 O4 and their products from low-temperature oxidation, Fe1− x Mg x Sb2 O4+ y, are described. Abstract : Three new materials of composition Fe1− x Mg x Sb2 O4 ( x = 0.25, 0.50, 0.75) with the tetragonal schafarzikite structure have been synthesised. Magnetic susceptibility measurements suggest that Fe1− x Mg x Sb2 O4 ( x = 0.25, 0.50) are canted antiferromagnets whilst Fe0.25 Mg0.75 Sb2 O4 is paramagnetic. The magnetic ordering temperatures decrease as the Mg 2+ concentration increases. The materials form oxygen-excess phases when heated in oxygen-rich atmospheres at temperatures of ∼350 °C. 57 Fe Mössbauer spectroscopy shows that the oxidation process involves the oxidation of Fe 2+ to Fe 3+ . Powder neutron diffraction confirms the location of the excess oxygen within the structural channels and reveals a change in magnetic order at low temperatures from A-type (magnetic moments along 〈100〉) for Fe1− x Mg x Sb2 O4 to C-type (magnetic moments along [001]) for the oxidised materials. The change is attributed to a weakening of the antiferromagnetic exchange interactions between edge-linked FeO6 octahedra for the Fe 3+ -containing materials.