纳米AgI-多孔SiO_2复合材料的制备及其性能研究

STUDY OF PREPARATION AND PROPERTIES OF NANO-SCALE AgI-POROUS SiO_2 COMPOSITES

用KI溶液浸泡溶胶 -凝胶法制备的掺Ag+ 的SiO2 凝胶 ,经 5 0 0℃热处理后获得分散均匀的纳米AgI -SiO2 复合体系。用X射线衍射、扫描电镜、紫外 -可见反射光谱以及复阻抗谱等分析手段研究了其结构、形貌、光谱特性和离子电导性质。结果表明 ,复合体系中AgI为β,γ相混晶结构 ,其粒径在 2 0～ 40nm之间。AgI -SiO2 复合体系的光谱吸收边与纯AgI及纯SiO2 不同。复合体系的室温电导率比纯AgI提高约 1～ 2个数量级 ,同时AgI的α β相变点滞后约 13℃。用界面效应和变形极化效应解释了体系电导率的提高 。

Well-distributed nanometer AgI-SiO2 composites were synthesized by dipping the sol-gel derived Ag+ ion-containing SiO2 matrix in the KI solution, after the heat treatment of 500°C. X-ray diffraction, scanning electron microscopy, UV-Vis reflectance spectroscopy and complex impedance spectroscopy were conducted to investigate the structure, morphology, optical properties and ionic conductivity of the composite. The acquired AgI particles, with average sizes of 20-40 nm, are mixtures of β phase and γ phase. The absorption edge of the AgI-SiO2 composite is different from both pure constituents. The room temperature conductivity of the composite is 1-2 orders of magnitude larger than that of pure AgI, and the α-β phase transition of AgI suffers a lag of about 13°C. The interfacial effect and the deformative polarization are adopted to explain the increase of the conductivity, while the elastic effect is suggested to be responsible for the phase transition lag.