Preparation Of Photonic Crystal Materials And Its Application

Photonic bandgap (PBG) crystals have received considerable attention over the past decade since the concept was first proposed (independently) by Yablonovich and John in 1987. Among numerous nanofabrication strategies, the self-assembly approach is a very possible way to create photonic crystals with complete photonic band gap (CPBG) in visible wavelengths. But in decades, silica and PS spherical colloids have been synthesized for photonic crystal applications because of limitation of fabrication technique. The possible candidate for creation for CPBG in visible wavelengths is the core-shell materials. The main research work in the research can be summarized and demonstrated as follows:(1) In this chapter, we did some research producing the colloidal crystals with modified vertical deposition method-isothermal heating evaporation induced self assembly (IHEISA) method. With the change in silica sphere size, we can get colloidal crystals with same quality. And stop bands are red-shifting for larger spheres packing with larger lattice constants. By controlling colloidal concentration, it is possible to vary the thickness of the films from a few layers to hundreds of layers. Finally, the capability of IHEISA to produce binary colloidal crystal films was demonstrated.(2) We presented a modified electroless plating method to make continuous silver nanoshells through a similar, but simple process. Using this method, complete silver nanoshells on silica partcles were prepared and characterized. And the optical properties of the colloidal crystals composed of silica doped silver composite particles were investigated under thermal treatment. At last, we tried to fill the pure silica colloidal crystal with metal silver.(3) As shown in our previous reports, use of mixed solvents has successful synthesize smooth and homogeneous titania shells on PS spheres. The goal of our research was to extrapolate this mixed solvents method to zirconia as zirconia precursor has similar molecular structure with titania precursor. The influence of the different catalyst with deionized water or ammonia and the volume fraction of acetonitrile in the mixture were investigated systematically. The shell thickness of the zirconia-coated polystyrene spheres was found to be correlated in a quasilinear fashion with the concentration of zirconium n-propoxide. Then corresponding zirconia hollow particles were prepared through calcinations.