Investigation of Charge-Ordered Barium Iron Fluorides with One-Dimensional Structural Diversity and Complex Magnetic Interactions.

Three mixed-valence barium iron fluorides, BaFeF, BaFeF, and BaFeF, were prepared through hydrothermal redox reactions. The characteristic structures of these compounds feature diverse distributions of FeF octahedra and FeF groups. BaFeF contained one-dimensional infinite [FeFeF] double chains, comprising corner-sharing octahedra along the direction; BaFeF contained one-dimensional [FeF] double chains, consisting of corner-sharing octahedra along the chain (-axis direction) and corner-sharing octahedra vertical to the chain, while BaFeF revealed three-dimensional (3D) frameworks that consist of isolated edge-sharing dinuclear FeF units linked via corners by FeF octahedra. Magnetization and Mössbauer spectroscopy measurements revealed that BaFeF exhibits an antiferromagnetic phase transition at ∼11 K, where ferrimagnetic [FeFeF] double chains are arranged in a paralleling manner, while BaFeF shows canted antiferromagnetic ordering at ∼32.5 K, leading to noncollinear spin ordering.