Tungsten and Oxygen

The tungsten-oxygen system is rather complex. Besides the stable stoichiometric binary oxides (WO₃, WO_2.9, WO_2.72, and WO₂); and the stoichiometric tungstates and acids, a variety of nonstoichiometric, fully oxidized and reduced compounds exists.

In the fully oxidized state (W⁶⁺) the octahedral coordination dominates (WO₆). The tungsten atoms are situated in the center of octahedrons and are surrounded by six oxygen atoms arranged at the comers. A-s long as all tungsten ions are hexavalent, these octahedrons are only comer-sharing. However, as the oxygen-to-tungsten ratio decreases, which occurs on reduction (transition to lower oxides), the octahedral become more and more intricately joined in combinations of corner-, edge-, and face-sharing.

Please visit www.tungsten-powder.com to get more information.