Preparation And Application Of Three-Dimensional Ordered A₂B₂O₇ Macroporous Complex Oxides

Three-dimensionally ordered macroporous (3DOM) material developed in recent years is a novel material,and has intrigued many researchers both in physics and chemistry communities because of its potential applications as photonic crystals, catalyst, supports, and electrodes etc. Colloidal crystal templating method is usually used to fabricate 3DOM materials,which generally involves three steps, namely, assembly of template from uniform monodisperse beads, deposition of desired precursor inside the template and finally removal of the template .So far, many kinds of 3DOM materials have been fabricated by this method, such as oxides, chalcogenides, non-metallic and metallic elements, alloys, hybrid organosilicates, and polymers. However, applications of these materials still face some challenges such as improving the pore wall compactness and mechanical stability, forming ordered stucture in large scale, and finding simple synthesis route to decrease synthesis cost. It is expect that new preparation methods and new composition 3D0M solids providing additional functionality will be emerging continually, and then will move closer to desired applications.In the present study, a nitrates route for fabrication of 3DOM metal complex oxide materials has been explored. The absract has been described as following:1. Synthesis of monodisperse polystyrene (PS) beads and assembly of colloidal crystal. PS beads with diameter of 260, 277, 583 and 640 nm were prepared using an emulsifier-free emulsion polymerization technique. Colloidal crystal template was assembled by a natural sedimentation and a centrifugation method. SEM observation shows that the PS beads have high monodispersity and the colloidal crystal has a face-centered-cubic (fcc) lattice. Compared with the centrifugation method, the natural sedimentation method obtained the colloidal crystal with lower defect density.2. Nitrates route for fabrication of 3DOM materials. Using nitrates as precursors, La₂Ti₂O₇, La₂Zr₂O₇ were fabricated. The role of alcohol and citric acid in the precursor solutions was decribed. Especially, the addition of citric acid may significantly improve the formation of 3DOM skeleton. SEM observation indicates that in the materials the...