Preparation methods of tungsten bronze are electrolysis method, wet chemical method, thermal reduction method. Electrolyzed molten tungstate and tungsten oxide system can obtain high-quality single-crystal tungsten bronze sample, and be able to effectively control the content of M element and the doping element of the sample. But the preparation time of electrolysis method is long and productivity is low, which can not meet the actual requirements of the application. Wet chemical has caught much attention because of the relatively low synthesis temperature, good crystallized state of tungsten bronze product and other characteristics, but the preparation conditions are harsh and preparation period is too long. Thermal reduction method is that generally mix tungsten trioxide, tungsten simple substance and metal M with appropriate proportions, and heated in a vacuum or under an inert atmosphere, the reaction temperature is generally about 1000 ℃. Thermal reduction method is the primary method for preparing tungsten bronze for earlier, the disadvantages are that it requires high temperature and products quality is difficult to control.

 

Ball milling the solid phase reaction method is to mix K₂WO₄ and WO₃ powders ball milled under vacuum solid phase reaction, the single-phase K_{0. 27}WO₃ tungsten bronze polycrystalline samples are obtained at 750 ℃. The synthetic method is simple and efficient.

 

After being ball milled, the mixing tablet material melted at 800 ℃, while it maintained the original massive at 750 ℃, products after vacuum solid-phase reaction were dark blue with no obvious impurities. Figure 1 is the XRD pattern of sample preparation. As can be seen from the figure, the reaction product at 750 ℃ and 800 ℃ are hexagonal structure, and the position of diffraction peak and intensity are exactly the same as the diffraction data of potassium tungsten bronze K_xWO₃ (0 <x <0. 33) JCPDS standard card. Which means the monophasic of the samples prepared by ball milled solid phase reaction is pretty good.