Synthesis of a Ferrolite: A Zeolitic All-Iron Framework

Crystals of the first sodalite-type zeolite containing an all-iron framework, a ferrolite, Ba₈(Fe₁₂O₂₄)Na_y(OH)₆⋅x H₂O, were synthesized using the hydroflux method in nearly quantitative yield. Ba₈(Fe₁₂O₂₄)Na_y(OH)₆⋅x H₂O crystallizes in the cubic space group (Formula presented.) with a=10.0476(1) Å. Slightly distorted FeO₄tetrahedra are linked to form Fe₄O₄and Fe₆O₆rings, which in turn yield channels and internal cavities that are characteristic of the sodalite structure. Barium, sodium, and hydroxide ions and water molecules are found in the channels and provide charge balance. Magnetic measurements indicate that the ferrolite exhibits magnetic order up to at least 700 K, with the field-cooled and zero-field-cooled curves diverging. Analysis of the⁵⁷Fe Mössbauer spectra revealed two spectral components that have equal spectral areas, indicating the presence of two subsets of iron centers in the structure. Dehydrated versions of the ferrolite were also prepared by heating the sample.