A new tungsten trioxide hydrate, : Preparation, characterization, and crystallographic study

A new hydrate of tungsten trioxide, WO3 · 13H2O has been obtained by hydrothermal treatment at 120°C of an aqueous suspension of either tungstic acid gel or crystallized dihydrate. This hydrate has been characterized by different methods. A crystallographic study was carried out from X-ray powder diffraction. The hydrate crystallizes in the orthorhombic system: a = 7.359(3) Å, b = 12.513(6) Å, c = 7.704(5) Å, Z = 12. The existence of structural relationships between the hydrate, WO3 · 13H2O, and the product of dehydration, hexagonal WO3, has permitted us to propose a structural model in agreement with the experimental data. WO3 · 13H2O must be regarded as an interesting compound because its dehydration leads to a new anhydrous tungsten trioxide, hexagonal WO3.