Preparation and formation mechanism of dawson structure (NH4)6P2Mo18O62•12H2O nano-powders by solid state reaction at room temperature

(NH4)(6)P2Mo18O62.12H(2)O nano-powders were prepared by the solid state reaction Of H6P2Mo18O62.23H(2)O with (NH4)(2)C2O4.H2O at room temperature. The nano-powders were characterized by elemental analysis, FTIR, XRD, TEM, TG-DTA and BET techniques. The experimental results indicate that the nano-powders were found still to exhibit Dawson structure and had the mean grain size of 40 nm and BET specific surface area of 143.9 m(2).g(-1). The heteropolyanion had a higher thermal stability at a temperature below 445 degreesC. In this solid state reaction, grinding and reaction thermal energy could accelerate the speed of reactant molecular diffusion and product molecular nucleation while decreasing the particle's size, water of crystallization of reactants and product H2C2O4. 2H(2)O played a key role in forming the small size (NH4)(6)P2Mo18O62.12H(2)O nano-powders.