Nanostructural Studies of Carbon, Bismuth and Other Materials

该项目的目标是通过研究纳米结构材料中发现的新现象，以及在其体积或晶体形式中未发现的特定纳米结构材料的新特性，增加对新材料和结构的理解。将研究的纳米结构材料特有的现象包括量子限制诱导量子线中半金属到半导体的转变，以及与碳纳米管的一维电子态密度相关的现象。特定材料的特殊纳米结构性质，如铋、碳纳米管、二硫化钼和独特形式的碳，将被研究。本文将系统地研究铋纳米线的电子结构与线径、晶向、温度和磁场的关系，特别关注小直径（小于100 nm）铋线的半金属到半导体的转变。利用各种纳米输运和光学技术，测量在压力下填充阳极氧化铝孔隙制备的铋纳米线的性能，并通过x射线衍射、透射电镜和扫描电镜技术对纳米线进行结构表征。光学研究也将进行，以研究这个1-D系统的电子结构。为了获得碳纳米管一维电子结构及其声子色散关系的定量信息，将对碳纳米管的一阶和二阶共振拉曼光谱进行系统的研究。通过对聚对苯（PPP）进行热处理获得的新型碳材料的微观结构/纳米结构与性能之间的关系进行实验和理论研究，以解释为什么该体系对锂具有如此高的亲和力，特别是该材料在锂离子电池中的应用。这项研究将在基础层面上为纳米结构材料的重要方面贡献基础材料科学知识。从研究中获得的基本知识和理解有望通过为设计和生产改进的材料以及纳米结构构建块的材料组合提供基本的理解和基础，从而有助于提高先进材料的性能和稳定性。该计划的一个重要特点是通过培养学生在基础材料科学和相关技术领域的研究和教育的整合。＊＊＊

9804734 Dresselhaus The goal of this project is to provide increased understanding of novel materials and structures through the study of new phenomena only found in nano-structured materials and new properties of specific nano-structured materials not found in their bulk or crystalline forms. Phenomena specific to nano-structural materials that will be investigated include the quantum confinement induced semimetal-to-semiconductor transition in quantum wires, and phenomena associated with the one-dimensional electronic density of states of carbon nanotubes. Special nanostructural properties of specific materials, such as bismuth, carbon nanotubes, MoS2, and unique forms of carbon, will be investigated. A systematic study will be made of the electronic structure of bismuth nanowires as a function of wire diameter, crystalline orientation, temperature and magnetic field, with particular attention to the semimetal-to-semiconductor transition in small diameter (less than 100 nm) bismuth wires. A variety of nano-transport and optical techniques will be used to measure the properties of bismuth nanowires prepared by filling the pores of anodic alumina under pressure, and structurally characterizing the nano-wires by x-ray diffraction, TEM, and SEM techniques. Optical studies will also be undertaken to study the electronic structure of this 1-D system. A systematic study of the first and second-order resonant Raman spectra of carbon nanotubes will be carried out in an effort to gain more quantitative information of the 1-D electronic structure of carbon nanotubes, and their phonon dispersion relations. Experimental and theoretical studies of the relation between microstructure/nanostructure and the properties of novel carbon materials obtained by the heat treatment of poly-para-phenylene (PPP) will be carried out to explain why this system has such a high affinity for lithium, with particular reference to the application of this material for use in lithium ion batt eries. %%% This research will contribute basic materials science knowledge at a fundamental level to important aspects of nanostructured materials. The basic knowledge and understanding gained from the research is expected to contribute to improving the performance and stability of advanced materials by providing a fundamental understanding and a basis for designing and producing improved materials, and materials combinations from nanostructure building blocks. An important feature of the program is the integration of research and education through the training of students in fundamental materials science and related technological areas. ***