Direct synthesis and single crystal structure determination of cubic pyrochlore-type tungsten trioxide hemihydrate, WO3 · 0.5H2O

Cubic pyrochlore-type WO3 · 0.5H2O has been synthesized hydrothermally directly from solution and its crystal structure determined by X-ray diffraction of a single crystal: space group Fd3m, a = 10.305(3) Å, Z = 16. The structure contains corner-sharing WO6-octahedra, leaving tunnels along the [110]-directions, in which the water molecules are located. Dehydration yields cubic pyrochlore-type WO3, which transforms into the monoclinic modification at higher temperature.