Mixed-surfactant Assistant Synthesis Of Tungstate Nanomaterials

In the past few years, the materials with nanometer scale have attracted much interest owing to their potential application in optical, conductive/superconductive, catalytic and biological applications. Therefore, manipulating the morphology and architecture of nanomaterials is always the study focus of scientist. Up to date, lots methods have been developed to fabricate nanomaterials, and in which the surfactant-assisted microemulsion system is an ideal reaction medium to the synthesis of nanomaterials. A variety of nanomaterials with different morphologies and uniform size have been prepared successfully with this kind of system.In recent years, metal tungstate nanostructures have attracted much attention due to their structural properties and promising applications. In this paper, with mixed surfactants N-cetyl-N,N,Ntrimethyl-ammonium bromide (CTAB) and polyvinylpyrrolidone (PVP) as structure directing reagent , PbWO₄ and CaWO₄ nanocrystals with different morphologies were fabricated via an one-step aqueous route. The effects of reaction parameters, such as reaction time, reactant concentration, surfactant concentration, temperature, on the morphology of the products were investigated and the photoluminescence of the products was also studied. The formation mechanism of the products is proposed reasonably.Moreover, Pb²⁺ doped CaWO₄ crystals and Ca²⁺ doped PbWO₄ crystals were synthesized by the same method assisted by CTAB and PVP. And it is found that the doping of Ca²⁺ have significant effect on the morphology and property of PbWO₄ crystals, whereas the Pb²⁺ ions make less effect on the CaWO₄ crystals, which may be related to the vacancies in the PbWO₄ crystals.The products were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), and X-ray diffraction (XRD) and Fluorescent spectra.