A New Synthetic Fluoride Phosphate of Mixed-Valence Iron: Cs₈Fe₈³⁺Fe₇²⁺F₁₀(PO₄)₁₂

The title compound, octacaesium pentadecairon decafluoride dodecaphosphate, was prepared by hydrothermal methods. The structure contains three types of Fe polyhedra (octahedra, tetrahedra and five-vertex polyhedra) which share vertices to form two-dimensional `branched' layers approximately parallel to the (120) plane. These layers are linked into a framework by PO₄ tetrahedra. The Cs atoms occupy holes in the mixed Fe/P framework.

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