单晶金属纳米线的制备及其超导性能研究

Superconducting technology as the high and new technology of strategic importance of the 21th century has become an international research hot. Especially the nano superconductors with characteristic physical properties has attracted extensive attention recently. Factors affecting the superconductivity such as quantum fluctuations, thermal disturbances and so on are very sensitive to the size of the nano superconductors, which will lead to unique properties such as the quantum fluctuated phase slip(QPS) and paramagnetic Meissner effete different from bulk materials. However, as limited by the material fabrication and measurement, there are still many challenges in the study of nano-superconductivity, such as the QPS and lattice distortion effects on the high Tc superconductors at nanoscale, the morphology controllable synthesis of nano-superconductors and so on. This study will focus on the above challenges: fabrication of high quality single crystal superconducting nanowires at mild working condition and forming effective methods of synthesis these materials by investigated the mechanism; research factors affect to superconductivity of the single crystal nanowires, and discussing its superconductive mechanism to improve the critical temperature and critical current density which will provide theoretical basis for research and development of new high Tc superconductors.

超导技术作为21世纪具有经济战略意义的高新技术已成为世界性的研究热点，尤其是近年来纳米超导体系以其特有的物理性质而引起人们的广泛关注。对于纳米超导材料，样品尺寸的减小将使量子涨落、热扰动等因素对于体系超导电性的影响变得极为显著，导致超导态的量子相滑移(QPS)、Meissner态下的磁通再入等不同于块材超导体的性质出现。但是受到材料合成、测试手段等的限制，如何实现纳米超导体形貌的有效控制合成以及纳米超导体系的超导机理等一直是该领域研究亟待解决的问题。本课题针对上述问题，在已有成果基础上研发工艺操作简单、反应条件温和的有效制备形貌及尺度可控单晶金属超导纳米线的方法体系，并力争提高其临界温度和临界电流密度；研究量子效应、微观晶格结构、热扰动等因素对材料超导性能的影响，并找出规律，在超导机理探讨方面力争有所突破，为高温超导机理研究及新型超导材料研发提供理论和数据支持。

本研究在液相体系中温和条件下有效制备出高质量单晶Sn纳米棒，通过对反应条件的精确控制得到了三种不同结构的单晶锡纳米材料，分别是八面体Sn纳米颗粒，长径比为7:1和4:1的单晶Sn纳米棒，高质量1D单晶纳米线为研究准一维尺度内超导现象提供了良好模型，Sn纳米棒超导性能研究显示其超导温度Tc由体相材料3.7K提高至5.5K，临界磁场Hc由体相材料0.03T大幅提高至3T，研究认为对于直径较小的1D纳米结 构，超导表面层对材料超导性能的提升具有重要贡献，对进一步认识纳米尺度超导金属的超导性能具有重要价值；研究还在在单晶Sn纳米结构制备基础上成功得到长1微米以上直径100-200nm的单晶铅纳米线。另外，在Nb及In金属纳米线制备探索过程中还得到了新型结构的孔状Nb2O5单晶纳米线及刚玉型孔状In2O3纳米球，其光催化性能研究表明，孔状Nb2O5纳米线的带隙宽度相比于体相材料由3.4ev降至2.94ev，具有可见光响应，对紫外光下和可见光下均可对RhB进行较好的降解，可见光下孔状Nb2O5纳米线光解水制氢亦表现出优异的性能，产氢速率达243.8 μmol g−1 h−1，远高于无孔Nb2O5纳米线和P25，证实该新型孔状结构为空穴的产生提供了良好路径，使得电子-空穴复合率降低，电子和空穴的运输环境得到优化，从而提高了光催化性能，该材料优异的光催化性能使其在相关领域具有重要的应用前景；刚玉型孔状In2O3纳米球紫外光降解RhB性能也有所提升。研究采用静电纺丝法对已制备出的氧化锡纳米颗粒进行纺丝成功制备出超长氧化锡纳米线，为单晶Sn及其他超导金属超长纳米线的制备及可能的相关应用奠定了基础。