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WEB Vacancy Segregation to Twist Grain Boundaries in Diamond-cubic Covalent Crystals

Wednesday (01.01.2020)
00:15 - 00:30
Part of:

Harsh radiation environments cause high density of point defects in crystalline materials resulting in materials ageing and degradation. The extraordinary high radiation damage resistance of nanostructured materials with high interface density indicates the important role of interfaces as sinks for vacancies and/or interstitials. Therefore novel radiation resistant materials may exploit the interaction of point defects with interfaces. The segregation behavior depends not just on the macroscopic interface characteristics (i.e., misorientation, interface plane inclination, atomic misfit) but mostly on the precise local atomic structure, resulting in emerging patterns of preferred segregation and adsorption sites along the interface. These patterns determine the distribution of radiation point defects from the bulk into the interface and its the sink-efficiency and resilience to radiation-induced aging.

Using atomistic simulations, the emerging atomistic structure-property relation is established in diamond cubic carbon and silicon (111) small and high-angle twist grain boundaries, thus addressing interface formation energy and segregation behavior. We will present the crucial role of the environment-dependence in the used interatomic potentials and predict the transition from glide to shuffle planes of twist grain boundaries in covalent materials. The implications are demonstrated for vacancy segregation. The variation of interatomic potential and materials shows the generality of our observations, thus highlighting the role of crystallographic constrains on the segregation patterns imposed by the purely geometric dichromatic patterns.

Dr.-Ing. Carolina Baruffi
École Polytechnique Fédérale de Lausanne EPFL
Additional Authors:
  • Dr. Christian Brandl
    University of Melbourne