Violet tungsten oxide(VTO) is also called tungsten violet oxide (TVO). TVO is manufactured by calcination of APT under more or less reducing conditions which vary from producer to producer. It is not a chemically defined compound, but consists of various different constituents, like trioxide, tungsten bronzes and different lower tungsten oxides. The relative amount of these compounds in TBO depends on the calcination parameters.
Violet tungsten oxide is a finely divided blue-violet crystalline powder. It is produced by rotary calcining ammonium paratungstate at closely controlled temperatures in a reducing atmosphere. CTOMS produces two standard grades differing mainly in oxygen content. Blue tungsten oxide is used primarily for the production of tungsten metal powder and tungsten carbide.
Viloet tungsten oxide is also used to manufacture ultra-fine tungsten powder or nano-tungsten powder.