Fabrication And Characterize Of Three-Dimensional Macroporous Phosphates Materials By Colloidal Crystal Template Method

Three-dimensional ordered macroporous （3DOM） materials not only have great specificsurface area and high porosity, but also have singleness pore size and periodic pore structurearranged in3-dimension space. It can be applied to design and control micro-nanostructureand properties of many functional materials. In this paper,3DOM KTiOPO₄-SiO₂nanocomposite photonic crystals is for the first time synthesized. In addition, porousLi₃V₂（PO₄）₃materials were prepared by colloidal crystal templating process.Firstly, the KTiOPO₄（KTP） nanopowder and KTiOPO₄-SiO₂nanophase glass-ceramicshave been prepared by the sol-gel method. The structures of the materials were analyzed byX-Ray Diffraction （XRD）, Scanning Electron Microscope （SEM） and Transmission ElectronMicroscopy （TEM） techniques. Then the reaction mechanisms were discussed. The resultsshow that the precursor formed by modified Ti（OC4H9）4can soluble in water. As a result,the KTP powderis successfully synthesized in H2O solution. Also, the （K, Ti, P, Si）multicomponent transparent gels were obtained in ethanol solution. After heat treatment, KTPnanocrystals with the size in the range30⁵0nm are precipitated from the transparent gels,forming KTiOPO₄-SiO₂nanophase glass-ceramics consisting of nanocrystalline KTP andSiO₂glass.Sencondly, monodisperse polystyrene （PS） and poly（methyl methacrylate）（PMMA）spheres were synthetized by emulsifier-free polymerization. The prepared spheres wereassembly to ordered erystalline colloidal array （OCCA） by gravitational sedimentation,centrifugal sedimentation and vertical sedimentation methods. KTiOPO₄-SiO₂precursorsolutions were prepared by the sol-gel method starting from metal alkoxides, then theprecursor was infiltrated into the OCCA PS templates, and3DOM KTiOPO₄-SiO₂photoniccrystal materials were successfully obtained after removing PS template through calcining at750℃for5h. SEM images show that the the macroporous structure is highly ordered. TheXRD analysis shows the KTiOPO₄nanocrystals are precipitated in the3DOM materials.Finally, macroporous Li₃V₂（PO₄）₃has been prepared via a solution-based templatingtechnique. The templated Li₃V₂（PO₄）₃samples were characterized using SEM, XRD and electrochemical measurements. The result show that the resulted Li₃V₂（PO₄）₃characted byporous structure. The porous Li₃V₂（PO₄）₃exhibit better electrochemical performance than thatof pristine one. The elevated electrochemical performance can be attributed to the porousstructure, which can make the infiltration of electrolyte and lithium ion diffusion more easilyacross the Li₃V₂（PO₄）₃.