Feng Ding
Institute of Textile and Clothing, Hong Kong Polytechnic University, Kowloon, Hong Kong, PR China
Abstract: As a rolled up graphene, a carbon nanotube (CNT) owns a cylindrical hexagonal lattice structure. Applying the classical dislocation theory in a system with the unique symmetry allows us to see deep insight into many aspects of CNTs: structures, mechanical properties and even chiral angle controlled growth.
First I will introduce dislocation structures (e.g., edge dislocations, screw dislocations of different types and dislocation loops) in carbon nanotubes and the in situ observation of their climb and/or gliding.
Then I will present the role of a specific type of edge dislocation (pentagon-heptagon pair, or 5|7) in plastic relaxation of carbon nanotubes under tension and at high temperature. We show how the glide of 5|7 and a particular type of their pseudo-climb, with the atoms directly breaking out of the lattice, work concurrently to maintain the tube perfection. Comparison between the dislocation theory and classical molecular dynamic simulation also will be also discussed.
At the end, I will present our recent progress in CNT growth mechanism. Mimics the Burton-Cabrera-Frank (BCF) theory, well established for 3D-crystals, we propose that a SWNT of any chiral angle can be viewed as a perfect crystal (or an achiral SWNT) with a screw dislocation. Starting from the screw dislocation model, detailed analysis together with ab initio calculations lead to a conclusion that SWNT growth rate is proportional to the tube chiral angle. This appears in surprising agreement with experimental data widely observed.
Location: 606 conference room
Date and time: August 15th, 2011 2:00 P.M
Speaker
Feng Ding
Academic qualifications
Ph.D. 2002: Dept. of Physics, Nanjing University, P. R. China
Masters 1996: Dept. of Physics, Fudan University, P. R. China
Bachelor 1990: Dept. of Physics, Huazhong University of Sci. &ence Technol., China
Previous academic positions held (with dates)
Research Scientist Oct. 2005-Dec. 2008: Mechanical Engineer and Material Science Dept. Rice University, Houston, USA
Postdoctoral Researcher Jan. 2003-Oct. 2005: Chalmers University of technology and Gothenburg University, Gothenburg, Sweden.
Assistant Professor Jun. 1996--Feb. 1999 and Dec. 2001--Jan. 2003, Department of Physics, Qufu Normal University. Shandong, China
Research Interests
Dr.Ding’s recent research focuses on on nanomechanics, structure transformation and growth of fullerenes, carbon nanotubes and grapheme. He has published more than 70 SCI papers (15 of them are published in high impact journals, IF >7.0; 2 in PNAS, 4 in Phys. Rev. Lett., 3 in Nano Lett., 2 in JACS, …).
Five most representative publications in recent five years
F. Ding, A. R. Harutyunyan, B. I. Yakobson, Dislocation Theory of Chirality Controlled Carbon Nanotube Growth, PNAS, 106, 2506 (2009)
F. Ding, P.Larsson, J. A. Larsson, R. Ahuja, H. Duan, A. Rosén, K. Bolton, K., The Importance of Strong Carbon-Metal Adhesion for Catalytic Nucleation of Single-Walled Carbon Nanotubes, NanoLett., 8, 463 (2008)
J.-Y. Huang, F. Ding, B. I. Yakobson, Dislocation dynamics in MWNT wall, Phys. Rev. Lett. 100, 035503 (2008)
F. Ding, K. Jiao, Y. Lin, and B. I. Yakobson,How Evaporating Carbon Nanotubes Retain Their Perfection? NanoLett. 7, 681 (2007).
F. Ding, K. Jiao, M. Wu, and B. I. Yakobson, Pseudoclimb and dislocation dynamics in superplastic nanotubes, Phys. Rev. Lett. 98, 075503 (2007)
