Cesium Tungstate Preparation by Liquid Phase Method

Nano cesium tungstate is a new material that has been discovered in recent years. It has been widely applied in the field of transparent heat insulation film, in automotive insulation film, building glass membrane, sunshade and heat insulation industries.

The main direction of the study of cesium tungstate in China is the liquid phase method. The Chinese patent CN102320662A proposed the preparation of tungstate solution by the exchange of sodium tungstate ion, and then dissolving cesium carbonate to get a mixed solution. Adding citric acid as a reducing agent, in 180-200 ℃ high pressure reactor for 1-3 days to obtain the target cesium tungstate nanopowder, compared with the method of ethanol as solvent, the method reduces the reaction pressure and improves the safety factor. But the reaction time is up to 1-3 days, the production efficiency is low, the production cost is high.

For the high cost and low production efficiency of the disadvantages caused by using technology of high pressure reactor, Tracy and other scholars put forward to tungsten chloride, cesium chloride as raw materials, with oleic acid and oleyl amine as the solvent to obtain cesium tungstate nanoparticles in 300 ℃. The method does not require high temperature and high pressure special equipment, and the preparation process is simple and feasible. However, the cost of raw oleic acid and oleamine is high and subsequent use of toxic solvents such as toluene and acetone is needed, and the concentration of the reactants is very low and the production efficiency is low, so the process is not of practical industrial value.

In addition, some scholars have also obtained the cesium tungstate nano powder by the method of full liquid phase and heat treatment without high temperature. In particular the tungsten chloride and cesium hydroxide dissolved in anhydrous ethanol, a suitable amount of acetic acid was added to the system and the target was crystallized for 20 hours in a closed autoclave at 200 ℃, and the target cesiumtungstate nano powder was obtained. The method is simple and easy to operate with short flow, but the pressure of the reactor is too high (greater than 10MPa) and the reaction time is longer.

Although these methods have failed to accomplish the mission of low cost and scale production of cesium tungstate, they have provided valuable experience in the study of cesium tungstate. The so-called failure is the mother of success, but as the research continues to deepen, there will be more and better preparation methods in the future.

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