Nano particle size tungsten trioxide for producing heat insulating window glass may be prepared by hydrothermal reaction, in which sodium tungstate, urea and concentrated hydrochloric acid are used as raw materials. As the NH4+ produced by the thermal decomposition of urea can make the synthesized metastable hexagonal phase tungsten trioxide stable, it is necessary to study the effect of urea on the crystal structure of tungsten trioxide under stirring conditions at room temperature.
After the addition of urea, the solution was stirred at room temperature for 24h, and the resulting precipitate was washed and dried at 60°C for 12h. Then, the sample was subjected to XRD test and the results are shown below.
After comparing with the standard card, the analysis result showed that the obtained sample was a mixture of tungstic acid and orthorhombic hydrated tungsten trioxide. Since tungstic acid dehydrates under heating conditions, it is speculated that the orthorhombic hydrated tungsten trioxide may be produced by dehydration of tungstic acid during the drying process.
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