Nanostructural Studies of Carbon, Bismuth and Other Materials

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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. ***