Direct Atomistic Observation of Grain Boundary Sliding II. Silicon Including Boundary Glass Phase

摘要

A silicon (Si) grain boundary including a glass phase was produced by the bonding of nanometer-sized Si tips which surfaces were coated with glass Si oxide layers inside a 200 kV electron microscope using a piezo-driving specimen holder. Atomistic grain boundary sliding was then caused at room temperature. The sliding process was directly observed by time-resolved high-resolution transmission electron microscopy at spatial resolution of 0.2 nm and time resolution of 1/60 s. The glass phase at the center of the grain boundary showed viscous flow-like deformation during the boundary sliding. The thickness of the glass phase decreased and relative shift of the tips was varied during the grain boundary sliding. The internal regions of the Si tips were not deformed plastically or fractured when the thickness of the glass phase was more than about 1 nm corresponding to a few atomic layers. It was shown that the stress introduced during the sliding was relived by the deformation of the glass phase at the boundary.