Sol-gel method producing yellow tungsten oxide use ammonium paratungstate as precursor, add in ethyl and esters in a certain ratio. After reaction, tungstic acid solution is obtained. After a period of aging process, converts tungstic acid sol to gel, by dry, calcination tungstic acid, yellow tungsten oxide is obtained.
Yellow tungsten oxide produced by sol-gel method has smaller grain size. But it costs high so that is suitable for experiment or research institution instead of industrial production.
Sol-gel method is producing method under mild condition. The principle is converting metal oxides or hydroxide oxides solution into gel, after dry and calcination, needed oxide products are obtained. Sol-gel method is by using inorganic material or metal alkoxide as precursor, mixing these raw material in liquid phase, with hydrolysis reaction and condensation reaction, it will form stable transparent gel system in the solution. After seasoning, gel particles agglomerated gradually and form three-dimensional space structure gel. The structure is full of solvent without mobility and forms as gel.