AVS 52nd International Symposium
    Nanometer-Scale Science and Technology Tuesday Sessions
       Session NS-TuP

Paper NS-TuP41
Atomic-scale Studies of Friction and Nano-Indentation

Tuesday, November 1, 2005, 4:00 pm, Room Exhibit Hall C&D

Session: Nanometer Scale Science and Technology Poster Session
Presenter: T. Filleter, McGill University, Canada
Authors: T. Filleter, McGill University, Canada
S. Maier, McGill University, Canada
R. Bennewitz, McGill University, Canada
E. Meyer, University of Basel, Switzerland
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The development of Scanning Force Microscopy has provided us with tools to study friction and wear on the nanometer scale. The characteristic atomic stick-slip instability in friction force measurements is caused by the jump of the contacting tip from one atomic position to the next. Thermal fluctuations in the combined system of tip, surface, and force sensor play an important role for the development of the stick-slip behavior. We measured the friction force for atomic stick-slip friction of a nanometer-sized tip sliding on a KBr (100) surface in ultra-high vacuum. Our friction force microscope allows us to detect force fluctuations up to 3 MHz, well above the mechanical resonance of the force sensor. We could track thermal fluctuations and found that the duration of the slip event shows a broad distribution even for slips over neighboring atomic positions. The indentation of surfaces by sharp tips is a standard method used to determine hardness and elastic modulus of materials. Scaling these experiments to small lengths can probe the initial stages of permanent deformation. Atomic scale plastic deformation at crystal surfaces has been achieved and characterized by use of non-contact force microscopy in ultra-high vacuum. A sharp silicon tip, first implemented as a nano-indenter, was used to image the atomic structure of displaced material on Cu (100) and KBr (100) surfaces. Under nano-Newton loading conditions the debris reorganizes in crystalline terraces with the same orientation as the underlying crystal.