Synthesis and Characterization of a Cubic Iron Hydroxy Boracite

The cubic iron hydroxy boracite Fe3B7O13OH center dot 1.5H(2)O was synthesized from Fe2O3 and B2O3 under high-pressure/high-temperature conditions of 3 GPa and 960 degrees C in a modified Walker-type multianvil apparatus. The crystal structure was determined at room temperature by X-ray diffraction on single crystals. It crystallizes in the cubic space group F (4) over bar 3c (Z = 8) with the parameters a = 1222.4(2) pm, V = 1.826(4) nm(3), R-1 = 0.0362, and wR(2) = 0.0726 (all data). The B-O network is similar to that of other cubic boracites.