Nano-designing of Mg doped phosphate tungsten bronzes and SiO2 composite obtained by ultrasonic spray pyrolysis method

Abstract

In this study, the structure and substructure of SiO2-Mg phosphate tungsten bronzes, MgPTB, (MgHPW12O40 center dot 29H(2)O) obtained by ultrasonic spray pyrolysis method from a silica sol and a MgPTB solution, obtained by the ion exchange method, as precursors were investigated. The mechanism of the formation of aerosol droplets is discussed. Phase composition, structure and substructure of SiO2-MgPTB particles were investigated by X-ray powder diffraction (XRPD) analysis, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Good agreement between the theoretically predicted values for the mean diameters of particles and subparticles (1.27 mu m and 75.4 nm, respectively) and the experimentally obtained ones (1.17 mu m and 65-90 nm) was found. This agreement confirms the applicability of the model to get a satisfactory prediction of the most important data related to the nano-structural design of SiO2-MgPTB powders. (C) 2009 Elsevier B.V. All rights reserved.