A new cation- and vacancy-ordered Brownmillerite in the Ba–In–Fe–O system revealing hidden order in its cubic counterpart

Abstract

The synthesis and characterization of a previously unreported B-cation ordered Ba2InFeO5 brownmillerite, obtained by an unconventional ultra-high-vacuum method, are reported alongside its cubic perovskite-type counterpart. Neutron diffraction and total scattering studies reveal for both phases ordered oxygen vacancies together with a layered FeO4/InO6 leitmotif, which gives rise to suppressed magnetic susceptibility and low-dimensional magnetic behavior. This work shows that ultra-high vacuum synthesis allows B-cation ordering to get stabilized forming new brownmillerite and perovskite type oxides, establishing Ba2InFeO5 as a model system for studying isolated 1D-tetrahedral Fe3+ chains, magnetic frustration, and structure-magnetism relationships.