Ionic Conductivity of Gel Prepared Silicates

本研究将研究凝胶衍生碱性硅酸盐材料的传输特性，特别是离子导电性。这项研究处于化学和材料科学的交界处。高离子导电性要求高碱浓度。涉及醇盐和盐的溶胶-凝胶法是将高浓度碱加入硅酸盐的一种方法。溶胶-凝胶法是一种形成玻璃的低温方法，允许醇盐的混合物水解和聚合形成氧化物网络。氧化物网络在溶剂的存在下冷凝，溶剂可以通过自然蒸发从毛孔中移除。干燥后残留的微孔凝胶称为干凝胶。初步研究表明，微孔率对传输特性有影响，从而影响离子导电性。干凝胶对传输特性的影响有三个方面：1)微孔率和孔径的影响，2)质子导电性的贡献，3)微孔固体中相分离的影响。该项目的主要仪器包括复阻抗谱、氮吸附分析、傅里叶变换红外光谱和固态魔角旋转核磁谱。

This research will investigate the transport properties, in particular ionic conductivity, of gel-derived alkali silicate materials. This investigation lies at the interface between chemistry and materials science. High ionic conductivity requires high alkali concentrations. The sol-gel process involving alkoxides and salts is one way of incorporating high concentrations of alkali into silicates. The sol-gel process is a low temperature approach to glass formation, where a mixture of alkoxides is allowed to hydrolyze and polymerize to form an oxide network. The oxide network condenses in the presence of the solvent which can be removed from the pores by natural evaporation. The microporous gel which remains after drying is called a xerogel. Preliminary studies show that the microporosity has an effect on transport properties and, consequently, ionic conductivity. Three aspects of xerogels affecting transport properties are being investigated: 1) the effect of microporosity and pore size, 2) the contribution of proton conductivity, and 3) effect of phase separation in a microporous solid. Principle instrumentation for this project includes complex impedance spectroscopy, nitrogen sorption analysis, Fourier transform infrared spectroscopy and solid state magic angle spinning nuclear magnetic spectroscopy.