The monodisperse silica particles self-assembled colloidal crystals were used as templates to synthesize pH value and temperature responsive ordered macorporous hydrogels. The ordered structure arranged by the uniform pores and the pore-pore interconnectivity through the window channel is confirmed by SEM characterization. UV-Vis-near IR absorption experiment result reveals that the wavelength at the stop band peak is tunable within the whole visible spectrum via simply altering some parameters such as pH value and light incidence angle. This finding allows to design frequency-tunable photonic band gap materials.
Eu3+ activated CaWO4 was prepared by high temperature solid state reaction technique. Red afterglow was observed for in the CaWO4∶Eu after exciting with 254 nm light due to Eu3+ transition from 5D0 to 7FJ (J=0, 1, 2, 3,4). By the cal culation of the thermoluminescence spectrum of CaWO4∶Eu, we conclude that there were two types of trap centers: VCa″ was formed by substitution of Ca2+ by Eu3 + and complex traps were produced because of substitution of W6+ by Eu3+.
