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2012 年 01 月 16 日
Seminar - Nanomechanics of nanotubes and graphene by Prof. Boris I. Yakobson

Date: 16 January 2012 (Monday)

Time: 11:00 am – 12:00 pm

Venue: EF305, The Hong Kong Polytechnic University

Abstract:
There are common principles governing mechanical response of both sp2-based nanostructures of carbon, nanotubes and graphene. I will discuss this theme, reviewing earlier and very recent results on several developing topics. Linear and nonlinear elasticity, and how to define and compute the elastic moduli. Then we will cover the predictions and observations of plastic and brittle failure, with particular attention to the underlying atomistic mechanisms. Further theory includes the role of point defects and dislocations, as well as their mobility. Some of the relaxation processes in the lattice can be “reversed” from yield and fracture to fusion-welding of nanocarbons, observed in several experiments. Good progress in understanding and calculation thermal transport can be achieved from purely shell-mechanics viewpoint, that s neglecting optical phonons and attributing the heat transport fully to acoustic branches of the spectrum. Since presence of edge is the feature distinguishing graphene from CNT, special attention recently has been devoted to the edge energy and its instabilities, effects of chemical passivation and how it can control the chirality of tubes or direction of nanoribbons. Further, the grain boundaries are among recent developments, their energy g , p , p y gy and kinetic origins of formation, mechanical response, and experiments and theory of graphene fracture directionality.

Biosketch:
Boris I. Yakobson is a world-leading expert in theory and computational modeling of materials nanostructures, their synthesis, mechanics, defects and relaxation, transport and electronics. Presently, Karl F. Hasselmann Chair in Engineering, professor of Mechanical Engineering Engineering and Materials Science and professor of Chemistry Rice University Houston Texas and Materials Science, and professor of Chemistry, Rice University, Houston, Texas. PhD, 1982, from Russian Academy of Sciences. 1982-1989, Head of Theoretical Chemistry group at the Institute of Solid Materials of the Russian Academy. 1990-1999, on the faculty of the Department of Physics, North Carolina State University. His research, sponsored over the years by the National Science Foundation, Department of Energy, NASA, Department of Defense, Army Research Office, Air Force Research Laboratory and AFOSR, Office of Naval Research, as well as private industry and foundations, resulted in over 160 publications and six patents. Received Department off d  d  d f  h i f Energy Hydrogen Program Award, Nano 50 Innovator Award from Nanotech Briefs (Boston), Royal Society (London) Professorship Award, Department of Energy R & D Award, NASA Faculty Award. Yakobson has mentored a number of PhD students and postdoctoral associates, and serves on the editorial boards of several journals and steering committees.