Deformation twinning in silver nanocrystal - Dr. Wege Yang

OCTOBER 20, 2015

There are many difficult challenges to track the deformation process in a single nanoscale crystal under external stresses. New research co-led by scientist from HPSTAR, Dr. Wenge Yang  provides an in situ three-dimensional mapping of morphology and strain evolutions in a single-crystal silver nanocube under high-pressure conditions using coherent diffraction imaging (CDI) method.

Previous study by Dr. Wenge Yang et al., using Bragg CDI technique, visualized the strain andmorphology evolutions in a 400 nm sized gold under various high-pressure conditions (Nat. Commun. 4, 1680, 2013; http://www.aps.anl.gov/Science/Highlights/Content/APS_SCIENCE_20130411.php). This study, for the first time, combined CDI with high-pressure technique.

Following the high-pressure CDI measurement on nano-gold, Yang et al., applied the same techniques to single crystal silver nanocube to in-situ track the strain evolution and deformation process in the nanocrystals again. The high-special resolution of CDI enables the scientists to image the shape and lattice distortion inside nanocrystals in real conditions, and in real time. Diamond-anvil cell technique was applied to achieve the external shear stress for nanocube-silver. At shear stress of some 2 GPa, a serials of distortions are imaged in silver nanocube. Moreover,a split of a single silver nanocrystal was observed during the plastic deformtion at the same conditions, which is identified to be deformation twinning.

This work represents another step forward followed by the breakthrough of high-pressure structure  study in nanocrystals. “These  mean that the CDI method would be a unique in situ approach to study a nanocrystal’s response to external stress, said Dr. Yang, “it will facilitate the understanding and interoperation of the deformation mechanism of nanocrystals and thus provide characterization tool to boost the rational design and tuningproperties of nanomaterials”.

The results are publishedin recent Nano Letters.

Caption: Lattice distortion and deformation twinning in silver nanocrystal at ~2 GPa.