Study Of Preparation Of Single Crystalline Tin Nanowires

1-D single crystalline tin nanostructures(nanowires or nanorods) are ideal models to study electrical conductivity, thermal conductivity and superconductivity in quasi-1-D nanoscale. It is attracting increasingly attention worldwidely due to its great research and application value. So far, the main strategy to prepare 1-D tin nanostructure is high-temperature(500-1000℃) vapor deposition method which has high energy consumption and cost. Therefore, developing low-temperature green method to synthesize high-quality single crystalline 1-D tin nanostructure has become an urgent task. This work explored the low-temperature method to synthesize 1-D single crystalline tin nanostructures from the perspectives of MOCVD method and solution-phase method. It is found that 1-D single crystalline tin nanostructure with a !-Sn phase can be prepared in water-SDS-NaBH4 solution system. Detailed investigations were conducted to optimize the synthesis conditions including concentration ratio of precursor and capping agent, reaction atmosphere, reaction temperature, reaction time, and adding method and adding rate of reducing agent. Finally high quality single crystalline tin nanorods with an aspect ratio of 7:1(length: 450-500 nm width: 60-70nm) were obtained. It is found that the morphology of the nanocrystals is mainly controlled by reaction temperature, the adding rate of the NaBH4 and SDS concentration. Through precisely controlling the reaction conditions mentioned above, four kinds of nanocrystals including octahedral nanoparticles, irregular tin nanoparticles, long single crystalline tin nanorods(aspect ratio 7:1) and short single crystalline tin nanorods(aspect ratio 3:1) were obtained. Meanwhile, it is also found that the morphology of the tin nanocrystals is highly sensitive to reaction temperature in the low temperature range, which is different from other metal nanocrystals. UV-visible light absorption spectrums of the four nanocrystals were also investigated, and it was found that these nanocrystals with different morphology exhibited different optical absorption properties, which demonstrate the morphology’s effect on the nanocrystals’ property.