Nucleation and Growth of Single-Walled Carbon Nanotubes Catalyzed by Transition Metal Particles

Florida Agricultural And Mechanical University, Tallahassee FL

Investigators

Abstract

TECHNICAL SUMMARY: This award supports research and education in theoretical physics in an area related to nucleation and growth of single-walled carbon nanotubes (SWCNT) catalyzed by transition metal particles. The study is motivated by the unusual materials properties of these systems, particularly their remarkable electrical, mechanical, thermal and optical properties. SWCNTs are the best conductors of electricity and heat and have exceptional photophysical and chemical properties. The research intends to provide some of the essential understanding of the processes that occur in creating these materials so that the potential applications of SWCNTs may be realized. The area of particular emphasis includes the nucleation and growth of these materials but in the process researcher will identify processing avenues that make it possible to control the chirality and diameter of a SWCNT, two important parameters that determine whether a SWCNT is semiconducting or metallic. Researchers will use theoretical and computer simulation techniques to better understand the growth process of SWCNT and how to achieve the desired uniformities of coherent and defect-free SWCNTs with controlled diameter, chirality, length and wall structure. This research will focus mainly on analyzing and describing catalyzed CVD technique, which is the most promising of the three major techniques for mass production of SWCNTs. Computer simulations will provide insight into the growth processes which are difficult to monitor experimentally because they occur at temperatures much higher than room temperature, in the range of approximately 400 ? 1000 Kn where the high temperature results in a high pressure, adding to the difficulty of monitoring the atomic level dynamics involved during the experiment despite advanced nanoscale measuring techniques. Computational studies are therefore necessary in order to examine the stages of the growth and pave the way for a more controlled growth of SWCNTs In order to understand the factors and parameters determining the chirality and diameter of the SWCNTs, rigorous quantum mechanical simulations must be done. We intend to perform all?electron density functional theory (DFT) simulations at the generalized gradient approximation level (GGA). These calculations will serve as benchmarks for ab initio molecular dynamics (MD) calculations which can handle larger systems than the all electron DFT simulations as well as finite temperature calculations. In the final stage of these simulations tight binding molecular dynamics calculations will be performed for larger systems and larger time scales than ab initio MD. The proposed work has both educational and applied impact beyond the basic research. Scientifically, this award will impact related research and applied work to develop carbon based technology at Florida A & M University (FAMU). The computational work will complement the experimental work in the growth of SWCNTS at FAMU Center for Nanoscience and Nanotechnology. The proposed work also will complement the development of the FAMU High Performance Computing Center where a computer cluster is being acquired for high performance computing and the simulations. The educational consequence of this includes the development of computational nanoscience coursework. Participation of minorities in science is supported through this effort. FAMU, one of the leading HBCUs, has one of the four Ph. Ds in physics and this grant will support the training of minority students. The research that has a strong education component involving the training of graduate students and a continuation of the PI's long history of recruiting undergraduates in cutting edge research projects with publishable outcomes. NON-TECHNICAL SUMMARY: This award supports research and education in theoretical physics in an area related to nucleation and growth of single-walled carbon nanotubes (SWCNT). These ultra small tubes are seen as one of the key elements of future nanodevices. The study is motivated by the unusual materials properties of these systems, particularly their remarkable electrical, mechanical, thermal and optical properties. SWCNTs are the best conductors of electricity and heat and have exceptional optical and chemical properties. The research intends to provide some of the essential understanding of the processes that occur in creating these materials so that the potential applications of SWCNTs may be realized. The area of particular emphasis includes the nucleation and growth of these materials but in the process researchers will identify processing avenues that make it possible to control the structure of a SWCNT and the parameters that determine how a SWCNT is conducts electric current. Researchers will use theoretical and computer simulation techniques to better understand the growth process of SWCNT and how to achieve the desired uniformities and defect-free SWCNTs with controlled diameter, length and wall structure. This research will focus mainly on analyzing and describing the most promising techniques for mass production of SWCNTs. Computer simulations will provide insight into the growth processes which are difficult to monitor experimentally because they occur at temperatures much higher than room temperature, and at high pressure, adding to the difficulty of monitoring the experiments despite advanced nanoscale measuring techniques. Computational studies are therefore necessary in order to examine the stages of the growth and pave the way for a more controlled growth of SWCNTs. The proposed work has both educational and applied impact beyond the basic research. Scientifically, this award will impact related research and applied work to develop carbon based technology at Florida A & M University (FAMU). The computational work will complement the experimental work in the growth of SWCNTS at FAMU Center for Nanoscience and Nanotechnology. The proposed work also will complement the development of the FAMU High Performance Computing Center where a computer cluster is being acquired for high performance computing and the simulations. The educational consequence of this includes the development of computational nanoscience coursework. Participation of minorities in science is supported through this effort. FAMU, one of the leading HBCUs, has one of the four Ph. Ds in physics and this grant will support the training of minority students. The research that has a strong education component involving the training of graduate students and a continuation of the PI's long history of recruiting undergraduates in cutting edge research projects with publishable outcomes.