Hexagonal tungsten oxide ball (hex-WO3), which is the tungsten oxide ball with hexagonal crystal structure. Since the single crystal hexagonal tungsten oxide has an empty hexagonal space tunnel structure, the W contained compound will exit mixed valence states of W6+, W5+ and W4+ and so on, thus to make the overall compound in a balance charge state. This special structure and valence is making hexagonal tungsten oxide ball has well electro-optic effect and excellent electrical properties, thus it has widely been used in laser frequency doubling, optical signal processing, superconducting material, solid fuel cell and other fields.
A study was taking glucose and ammonium metatungstate (AMT) as the raw materials to prepare hexagonal tungsten oxide ball by solid - phase thermal decomposition method, which is controlling the crystal morphology of tungsten oxide ball by adjusting the temperature in the reaction process. The manufacture steps are as follow:
1. Weight the ammonium metatungstate and glucose in accordance with a specific mass ratio, the mass ratio of AMT: glucose is preferred of 1:2.5;
2. Grind AMT and glucose crystal to the average particle size of 10nm~200μm, then put them in quartz boat after mixed uniformly;
3. Put the quartz boat with the raw materials in a tube furnace with inert gas atmosphere, and then rise the temperature to 850°C~900°C by the program temperature controlling to sinter for 5~6 hours, then we get the product of hexagonal tungsten oxide ball after cutting down the current and natural cooling.
The particle size of hexagonal tungsten oxide ball obtained in this method is among 40μm~80μm, and there is no agglomeration between the spheres; moreover, the tungsten oxide nanorods are regularly attached to the surface of the ball, which have a length of 1μm~5μm. This solid - phase thermal decomposition method to prepare tungsten oxide has the benefits of less raw materials (AMT and glucose) required, simple ingredient and process, nom pollution to the environment, high purity of product, short cycle and small consumption of energy and so on, thus to be benefit for industrial production, also it has provided a new way for preparing nano materials at the same time.