Bi2Te3纳米线的液相法合成及其结构表征

Abstract

利用热电材料能够实现温差发电和热电制冷，所以可以有效地缓解日趋严重的能源危机，Bi2Te3目前是室温条件下热电性能最好的热电材料。材料的低维化能够很大程度地提升其自身的性能，Bi2Te3纳米线具有更好的热电转换效率。利用液相法能够很成功和方便地在实验室合成Bi2Te3纳米线，实验中先反应生成Te纳米线胶体溶液，然后再在其基础上合成Bi2Te3纳米线。热处理温度选定为170℃，研究发现加热反应的时间会显著影响所制备样品的结晶性。实验中按照不同的加热反应时间来分成三组进行对比，通过X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)分析其结构和形貌，对比得知加热90 min所制备的Bi2Te3纳米线的结晶度和产率都比加热30 min和60 min的要好，表明液相法合成Bi2Te3纳米线需要一个较长的反应过程，适量延长加热反应时间有助于获得较高结晶质量的Bi2Te3纳米线。 Thermoelectric materials, which can covert heat to electric energy for power generation and conversely con- vert electric energy to heat energy for refrigeration, thereby alleviate the growing energy crisis effectively.Bi2Te3 is currently the best thermoelectric material for room temperature applications. Materials of lower dimensions can be used to obtain better properties, and therefore,Bi2Te3 nanowires have higher thermoelectric conversion efficiencies. In this work, we prepared Bi2Te3 nanowires very conveniently by using the liquid-phase synthesis method. Firstly, we syn- thesized Te nanowires colloidal solution, and then synthesized Bi2Te3 nanowires on the basis of it. The heating tem- perature was optimally set at 170˚C, while it was found that the heating reaction time affected greatly the crystallinity of the Bi2Te3 nanowires. Three sample groups were divided according to different heating reaction time. After synthesis, we analyzed systematically their structures and morphologies by XRD, SEM, and TEM. The crystallinity and yield of the third sample group, whose heating reaction time is 90 min, is much better than those of the other two groups, namely 30 min and 60 min, indicating that a long reaction process is required for the liquid-phase synthesis of Bi2Te3 nanowires and thus lengthening appropriately the heating reaction time is helpful in achieving highly crystalline Bi2Te3 nanowires.