According the formula CsxWO3 (0 <x <0.33) of cesium tungsten bronze, the tungsten is in the reduced state in CsxWO3 system, and low-valence tungsten ions increases with the increase of cesium ions,, which shows a reducing atmosphere is required during the CsxWO3 synthesis and the reducing atmosphere for reducing the is required more with the increasing incorporation of cesium ions. In this experiment, use citric acid and ethanol as the reducing atmosphere, carboxyl or hydroxyl group of citric acid and ethanol can be oxidized into the carbon dioxide or carboxyl at high temperature and pressure, and W6 ⁺ is reduced to W4 ⁺ or W5 ⁺, Cs ions doped into the tungsten bronze structure to get CsxWO3.

 

Figure 1 shows XRD patterns of CsxWO3 powder synthesis of the different reaction times. Figure 1 shows, the structure of the synthetic powder is similar to hexagonal structure Cs0.32WO3 diffraction pattern of the standard card 83-1334, and diffraction peaks became more clear with the reaction time increasing, which indicates that the extending reaction time contributes to its crystal growth.

 

Figure 2 shows XRD patterns of CsxWO3 powder synthesis of the different concentrations of citrate precursor solution. Figure 2 shows, the higher the concentration of citric acid, the sharper the CsxWO3 synthesized diffraction peaks, which indicates that the citric acid content helps CsxWO3 crystals generation. Because citric acid on the one hand serves as a reducing agent in the course of the reaction and produce carbon dioxide gas after the reaction, to increase the reaction pressure; on the other hand, it acts as a dispersant, so that with increasing concentration of citric acid, water and heat active reaction gradually increased, prompting the growth CsxWO3 crystals.