G. Simon Case, Andrew L. Hector, William Levason, Richard L. Needs, Michael F. Thomas and Mark T. Weller
Sr2FeO3F and the novel phases Sr3Fe2O6F0.87 and Ba2InFeO5F0.68 have been prepared and their structures investigated by powder neutron diffraction methods. Sr2FeO3F crystallises with the T* modification of the K2NiF4 structure owing to oxide/fluoride ordering. Sr3Fe2O6F0.87 and Ba2InFeO5F0.68 are mixed valent phases prepared by reaction of anion deficient iron(III) materials with gaseous fluorine. Sr3Fe2O6F0.87 is a Ruddlesden–Popper type material which has been shown by Mössbauer spectroscopy to contain iron(III) and iron(V). Ba2InFeO5F0.68 is the first example of an iron oxyfluoride with a perovskite-type structure.