Abstract: (NH4)3PMo6W6O40 nanoparticles were synthesized by the solid state reaction of H3PMo6W6O40•23H2O with (NH4)2C2O4•H2O at room temperature. Its structure, particle size and appearance were characterized with elemental analysis, IR, UV-Vis, XRD, TEM, TG-DTA and BET techniques. The results show that (NH4)3PMo6W6O40 nanoparticles are found to exhibit Keggin structure, have a surface area of 167.6 m2•g－1, below 465 ℃, the nanoparticles have a higher thermal stability, the mean grain size is of the value of 10 nm. In this solid state reaction, grinding and reaction thermal energy can accelerate the speed of reactant diffusion and product nucleation and decrease the particle′s size, water of crystallization of reactants and product H2C2O4•2H2O play a key role of forming the small size (NH4)3PMo6W6O40 nanoparticles.

Key words: (NH₄)₃PMo₆W₆O₄₀, Nanoparticles, Solid state reaction at room temperature, Mechanism