均相三方碲硒纳米晶可控合成方法的研究

发布时间：2018-06-28 11:38

本文选题：半导体 + 纳米晶　；参考：《华中农业大学》2015年硕士论文

【摘要】：半导体纳米材料具有许多特殊的光学、电学、化学和磁学性质,这些性质很大程度上受到材料的形貌和尺寸的影响,因此可控的合成半导体纳米材料一直受到广泛的关注。碲、硒和碲硒晶半导体材料拥有低的熔点、良好的光导性、热电性能和氧化还原能力,在合成功能材料和纳米级设备的制备上展现出潜在的应用价值。但在目前的研究中碲硒晶纳米材料的研究并不多,而且其形貌多样性和合成方法有很大的改进空间。本论文研究了可控合成不同形貌的均相(homogeneous)三方碲硒纳米晶(trigonal Te/Se alloy nanocrystals,t-Te/Se ANCs)。我们采用常温水相法合成碲硒晶纳米材料,合成方法简单环保且可以大批量合成。主要研究结果如下:1.调控前体Te O2与H2Se O3的比例(x(Te:Se))合成形貌多样,纵横比、成分可控的t-Te/Se ANCs。通过调控x(Te:Se)的值,t-Te/Se ANCs主要会按照两种方式生长:第一种,当x(Te:Se)的值从200:1到100:1或者从2:1到1:1的时候,生长成独个三方碲硒纳米晶(trigonal Te/Se alloy single nanorods,t-Te/Se ASNRs);第二种,当x(Te:Se)从30:1到10:1的时候生长成三连体的三方碲硒纳米晶(trigonal Te/Se alloy tri-fold nanorods,t-Te/Se ATNRs)。这些纳米晶通过自籽结晶过程形成生长方向沿[001]方向生长的均相单晶。2.表征了t-Te/Se ANCs的紫外可见吸收光谱、晶体结构、组成成分和拉曼光谱。随着t-Te/Se ANCs长度和x(Te:Se)的变化,t-Te/Se ANCs的紫外、晶体结构、组成成分和拉曼也存在一系列规律性的变化。当t-Te/Se ANCs长度的减小时,t-Te/Se ANCs的紫外峰会发生红移。随x(Te:Se)值的减小,t-Te/Se ANCs的晶体结构,组成成分和拉曼光谱与三方硒(trigonal Se,t-Se)趋于相同。3.分析论证了不同形貌t-Te/Se ANCs自籽结晶过程的机理。从碲硒纳米晶不同反应阶段的透射电镜图看出,t-Te/Se ASNRs与t-Te/Se ATNRs的生长是两个不同的结晶成核过程。在t-Te/Se ASNRs的形成过程中,只存在一次成核结晶,t-Te/Se ASNRs由最初的小六棱柱(核子)逐渐结晶长大;而t-Te/Se ATNRs的形成是存在两次成核结晶过程,先结晶成核为小六棱柱,然后选择性的自动在小六棱柱的三个面结晶成核为另外的三个小六棱柱核子,随着这三个小六棱柱的长大最终形成t-Te/Se ATNRs。这可能是由于Te,Se两种元素有不同的化学和晶体学性质,因此两者最终形成的纳米棒的形貌会因两者的比例不同而有所不同。
[Abstract]:Semiconductor nanomaterials have many special optical, electrical, chemical and magnetic properties. These properties are greatly affected by the morphology and size of the materials, so controllable synthetic semiconductor nanomaterials have been widely concerned. Tellurium, selenium and selenium tellurium crystal semiconductor materials have low melting point, good photoconductivity, thermoelectric properties and redox ability, which show potential applications in the preparation of functional materials and nanoscale equipment. However, there is not much research on se Te nanocrystalline materials, and there is much room for improvement in their morphology diversity and synthesis methods. In this paper, trigonal Ter se alloy nanocrystals t-Ter se nanocrystals with different morphologies have been synthesized by controlled synthesis. Se Te nanocrystalline materials were synthesized by water phase method at room temperature. The synthesis method is simple and environmentally friendly and can be synthesized in large quantities. The main results are as follows: 1. The ratio of Te-O _ 2 to H _ 2Se _ 3 (x (: se) was characterized by various morphologies, aspect ratio, and controllable composition of t-Ter se ANCs. By regulating the value of x (team: se), t-Ter / se ANCs grow mainly in two ways: first, when the value of x (team: se) ranges from 200: 1 to 100: 1 or from 2:1 to 1:1, they grow into trigonal Ter. E alloy single nanorodst-TeSe ASNRs. From 30:1 to 10:1, the trigonal Ter. E alloy tri-fold nanorodsm t-Ter se ATNRs were grown from 30:1 to 10:1. These nanocrystals form homogenous crystal. 2. 2 in the direction of growth along [001] direction through the process of self-seed crystallization. The UV-Vis absorption spectra, crystal structure, composition and Raman spectra of t-Ter / se ANCs were characterized. With the variation of t-Ter / se ANCs length and x (team: se), there are a series of regular changes in the UV, crystal structure, composition and Raman of t-Ter / se ANCs. When the length of t-Ter / se ANCs decreases, the UV summit of t-TeP / se ANCs redshifts. With the decrease of the value of x (TeSe), the crystal structure, composition and Raman spectra of t-Te-Se ANCs tend to be the same as that of trigonal Sea-t-Se. The mechanism of self-seed crystallization of t-Ter / se ANCs with different morphologies was analyzed and demonstrated. Transmission electron microscopy (TEM) of selenium tellurium nanocrystals shows that the growth of t-Ter / se ASNRs and t-Ter / se ATNRs are two different nucleation processes. In the formation of t-Ter / se ASNRs, there is only one nucleation and crystallization of t-TeP / se ASNRs, and the formation of t-Ter / se ASNRs gradually grows from the initial small hexagonal prism (nucleon), while the formation of t-Ter / se ATNRs is a process of two nucleation and nucleation, and the first crystallization is a small hexagonal prism. Then the nucleation of the other three small hexagonal prism nucleates automatically on the three sides of the small hexagonal prism, and as these three small hexagonal prisms grow up, the t-Ter / se ATNRss are finally formed. This may be due to the different chemical and crystallographic properties of the two elements, so the morphology of the nanorods formed by the two elements will be different depending on the ratio of the two elements.
【学位授予单位】：华中农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1

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