一种新的光致变色膜：Na2WO4-PAA-Glycerol体系研究

A method for preparing Na₂WO₄-PAA-Glycerol photochromic films was reported. The film was composed of Na₂WO₄, PAA and Glycerol, which were coated on a glass substrate. The film turned blue in the sun, and bleached to transparent in the darkness. The UV-Visible spectra showed strong absorbance at 300～500 nm, and the ABS changed signifanctly at 500～800 nm. The film showed the best photochromic behavior when n_Na2WO4∶n_PAA is 4%～5%. The mechanism was suggested that after irradiation, poly tunstate produced by Na₂WO₄ and PAA formed the tungsten blues. The tungsten blues were bleached due to oxidation back to poly tunstate by oxygen. The film showed not only an excellent photochromism property with rapid response and good reversibility, but also the simple techniques and good stability.     

BaWO4纳米线束的合成及其光学性质研究

High quality BaWO₄ nanowire bundles have been synthesized in toluene-sodium dodecylbenzene sulphonate (SDBS)-small amount PEG20000-H₂O reverse micelle system. XRD result shows that the obtained BaWO₄ belongs to tetragonal phase with scheelite structure. TEM results demonstrate that the obtained BaWO₄ nanowire bundles have high aspect-ratio (>650). The experimental results confirm that PEG20000 plays a key role for the formation of BaWO₄ nanowire bundles. Other factors which influence the morphology and crystallinity of the product are also briefly discussed. Moreover， the obtained BaWO₄ nanowire bundles exhibit strong photoluminescence centered at 397.3 nm with λ_ex=343.5 nm at room temperature， which is different from the bulk BaWO₄ crystals.