Ba2F2Fe1.5Se3: An Intergrowth Compound Containing Iron Selenide Layers

The iron selenide compound Ba2F2Fe1.5Se3 was synthesized by a high-temperature ceramic method. The single-crystal X-ray structure determination revealed a layered-like structure built on [Ba2F2]2+ layers of the fluorite type and iron selenide layers [Fe1.5Se3]2–. These [Fe1.5Se3]2– layers contain iron in two valence states, namely, FeII+ and FeIII+ located in octahedral and tetrahedral sites, respectively. Magnetic measurements are consistent with a high-spin state for FeII+ and an intermediate-spin state for FeIII+. Moreover, susceptibility and resistivity measurements demonstrate that Ba2F2Fe1.5Se3 is an antiferromagnetic insulator.