High purity violet tungsten oxide (WO2.72 or W18O49) is the VTO with very low impurity content and very high main content. Commonly, the high purity material refers to the new type material which has the higher chemical purity, less impurity content, and excellent physical and chemical properties compared to the conventional material; which is obtained by modern metallurgy technology under a super-clean environment. There are three aspects of meaning of the purity to the materials:
1. There is a close relationship between the property of substance and its purity;
2. The study on purity can assist to clarify the structure sensitivity property of the substance, the influence that impurities will cause on the defect, and other factors, and thus to create conditions for developing the property of a given material in advance and the designing new material;
3. With the continuous improvement of material purity, it will further reveal the potential performance of materials.
The purity of high purity violet tungsten oxide can reach to 99.95% (3.5N), 99.99% (4N); and if the production conditions, raw material and other factors are getting better controlled, then the purity of high purity violet tungsten oxide can even reach 5.5 N level, i.e. 99.9995%. There are variety labellings in different industries, and the general labelling is by number 9. Such as Purity is 5N represents the purity of 99.999%; the 4.5N represents the purity of 99.995%.