Structure and magnetic properties of the cubic oxide fluoride BaFeO2F

Fluorination of the parent oxide, BaFeO3−δ, with polyvinylidine fluoride gives rise to a cubic compound with a=4.0603(4) Å at 298 K. 57Fe Mössbauer spectra confirmed that all the iron is present as Fe3+. Neutron diffraction data showed complete occupancy of the anion sites, indicating a composition BaFeO2F, with a large displacement of the iron off-site. The magnetic ordering temperature was determined as TN=645±5 K. Neutron diffraction data at 4.2 K established G-type antiferromagnetism with a magnetic moment per Fe3+ ion of 3.95 μB. However, magnetisation measurements indicated the presence of a weak ferromagnetic moment that is assigned to the canting of the antiferromagnetic structure. 57Fe Mössbauer spectra in the temperature range 10–300 K were fitted with a model of fluoride ion distribution that retains charge neutrality of the perovskite unit cell.