Silica aerogels were prepared by sol-gel technique from industrial silicon derivatives （polyethoxydisiloxanes, E40）, followed by silylation and drying under ambient pressure. The specific surface area, pore size distribution and thermal conductivity of the silica aerogels were investigated and the results showed that the diameter of the silica particles is about 6 nm and the average pore size of the silica aerogels is 14.7 nm. The specific surface area of which is about 1000 m^2.g^-1 and the thermal conductivity is about 0.014 wm^-l.K^-1 at room temperature and pressure of 1.01×10^5 Pa. The Si-CH3 groups were also detected on the internal surface of the silica aerogels, which show hydrophobic. Silica aerogels derived by this technique is low cost and have wide applications.
Jun SHEN Zhihua ZHANG Guangming WU Bin ZHOU Xingyuan NI Jue WANG
Transparent mixed phase (1 - x)V2O5-xTiO2 (x=0,01,0.2,0.3,0.4) thin films were prepared on indium tin oxide (ITO) coated glass via sol-gel process. The films were characterized by cyclic voltammetry, optical spectroscopy, scanning electron microscopy, IR and X-ray diffractometer. Electrochemical lithium insertion/extraction showed that the porous structure of sol-gel (1 - x)V2O5-xTiO2 thin films exhibited good recharge ability of Li+/e- insertion/extraction process. For a 220 nm thick (1 - x)V2O5-xTiO2 film with 90% V2O5, the capacity of charge exchange reached 9 mC/cm2. In both Li+ intercalated and free states, the films were highly transparent to visible light. Such films have potential applications in counter electrodes for electrochromic smart windows and other electrochemical devices.
