Abstract:

In this talk I shall report on some of our recent progress in physical property measurements and corresponding structural characterization, at atomic resolution, of individual nano-materials under simultaneous nano-manipulation from applied fields.

First I shall introduce some innovative methods in measurements of new physical phenomena result from one dimensional quantum confinement of ultra thin metal on semiconductor films. With their innovative sample preparing method and STM analysis, our project colleagues have made a systematic study on superconductivity, surface activity, selective nucleation, Kondou effects, est., deduced from the variation of density of states near by the Fermi surface.

Then I shall present some new methods on in-situ observation, with atomic resolution, of structural evolution of nano-wires under simultaneous nano-manipulation in high resolution transmission electron microscopes. By employing this self-developed new method, we can conduct a continues tensile or bending of one dimensional nanowires and found, for the first time, the brittle-ductile transition at room temperature and extremely large plasticity behavior of both Si- and SiC-nanowires(NWs). In-situ electron microscopy study shows that the unusual large plasticity of Si- and SiC-NMs results from a strain-induced structural evolution process starting from defect generation, aggregation, and finally amorphouzation at the strain concentration region of the NWs. It is not only the first time to report on experimental observation of unusual large plasticity of Si- and SiC-NWs, but also the first to show a new phenomena for amorphous materials with large tensile plasticity from covalent nano-materials.

A special interest of my talk shall focus on the new characterization and investigation methods for one dimensional nanowires and two dimensional nano materials as ultra thin films. Some new characterization methods related to the electron energy loss spectrum and others shall also be introduced.
 
 
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