Fluorination of perovskite-related SrFeO3−δ

Structure and magnetic properties of the cubic oxide fluoride BaFeO2F

“…We have recently reported [4,5] on the fluorination of oxygen-deficient perovskiterelated SrFeO 3-δ to give a compound of composition SrFeO 2 F with a cubic unit cell and have formulated a model related to the pattern of substitution by fluorine on the octahedral arrangement of oxygen sites around iron in which SrFeO 2 F undergoes a magnetic transition around 300K from a low temperature state with random spin directions to an antiferromagnetic state. We have also prepared the related cubic phase of composition BaFeO 2 F and, in a preliminary neutron powder diffraction study, found it to exhibit G-type antiferromagnetic order at 298K [6].…”

Comparison of topotactic fluorination methods for complex oxide films

“…[26][27][28] 34,35 Recent work has demonstrated fluorination of epitaxial perovskites via the thermal decomposition of fluorine-containing polymers in close proximity to a ABO 3−δ film, 36,37 a technique adapted from fluorination processes carried out on bulk oxides. 26,38,39 In one approach, a poly(vinylidene fluoride) (PVDF) solution is spin-coated onto an as-grown, oxygen deficient film. 36 The oxide/polymer bilayer is then annealed in flowing O 2 to decompose the polymer, enabling F ions to diffuse into the film.…”

Perovskite-Related Oxide Fluorides: The Use of Mössbauer Spectroscopy in the Investigation of Magnetic Properties

“…Our initial work [7,8] in synthesising and characterising fluorinated cubic perovskite-related oxides used poly(vinylidene fluoride) for the fluorination of the oxygen deficient phase SrFeO3-d which, because of oxygen deficiency, distorts to an orthorhombic unit cell. The AMO3 unit cell, depicted in Figure 1 (n = infinity), contains strontium (green spheres) coordinated by twelve oxygen atoms whilst iron is located in an octahedral array of oxygen (red spheres).…”

“…The initial characterisation 7 by X-ray powder diffraction showed that fluorination resulted in a material with larger cell parameters consistent with the partial replacement of oxygen by fluorine (while X-ray diffraction suggested cubic symmetry, subsequent neutron diffraction studies showed that the cell symmetry was actually orthorhombic). 57 Fe Mössbauer spectroscopy demonstrated [7] that fluorination induced a reduction of the oxidation state of iron from Fe 4+ /Fe 3+ in SrFeO3-d to Fe 3+ in the compound SrFeO2F.…”

“…The randomness was associated with the substitution by fluorine on the oxygen anion site causing different superexchange Fe 3+ -O 2− -Fe 3+ and Fe 3+ -F − -Fe 3+ pathways. The significance of the work 7,8 is vested in it showing that the magnetic structure of SrFeO2F is significantly more complex than that of the antiferromagnetic structurally related PbFeO2F [9] in which the trans configuration of fluorine in the distribution of anions around Fe 3+ is favoured over the cis arrangement. The differences may be related to the lower temperature synthesis route to produce SrFeO2F in contrast to the high pressure, high temperature synthesis route needed to produce PbFeO2F.…”