快离子导体纳米碘化银的制备、结构及物性研究

The main purpose of this project is to explore new and effective approaches for synthesizing nanometer AgI, to investigate its physical, structural, electrical, and phononic properties as well as the different mechanism between nan- and normal AgI, and to promote the pplications of AgI-based ionic onductors. In the past three years, we have investigated:1).Synthesis of nanocrystalline γ-AgI with size of 7~12 nm by quenching molten AgI in liquid nitrogen at various quenching rates. The structure, ionic conductivity, thermal property, and band structure of nano-AgI were investigated. It is found that the ionic conductivity is about 2 orders of magnitude higher than that of normal AgI, and the β→α phase transition is second-order while that of normal AgI is a first-order one. Its band tail is also broadened. A new model was proposed to interpret these abnormal properties.2).Synthesis of well-distributed nano-AgI with size of 20~40 nm in mesoporous silica by sol-gel method combined with soaking. The ionic conductivity of AgI-SiO2 composite is about 1~2 orders of magnitude higher than that of pure AgI. Its α→β transition suffers a hysteresis of 13°C. The composite has two photoluminescence emissions at 340 and 510 nm at room temperature. 3).Synthesis of AgI-KI composite which has ionic conductivity 4 orders of magnitude higher than that of pure AgI at room temperature. The temperatures of both its α→β and β→α transition are about 15°C different from that of pure AgI. The composite material may find application in low-temperature solid batteries and electrochemical sensors. 4).Synthesis of nano-AgI by spray-desiccation process. However the attempt was ceased because of the very low efficiency (it will take about 4000 h for only 1g sample).

探索制备纳米AgI的优异方法。研究纳米AgI的物性、结构及电、声子特性与传统AgI的差异盎怼Ｒ云谛〕叽缒擅譇gI出现奇异物性。为AgI基离子导体更广泛应用寻求新路。深入对擅譇gI的研究将促进纳米快离子导体学及纳米材料学的基础理论研究，有可能为建立纳米快离子导体学开辟路子，对固体离子学的发展及固体离子器件的应用都有重大意义。