Fast Surface Dynamics on a Metallic Glass Nanowire.
basic_science · Level V
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- Record sourced from PubMed, PMID 34152730.
- Also identified by DOI 10.1021/acsnano.1c00500.
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Abstract
The dynamics near the surface of glasses can be much faster than in the bulk. We studied the surface dynamics of a Pt-based metallic glass using electron correlation microscopy with sub-nanometer resolution. Our studies show an ∼20 K suppression of the glass transition temperature at the surface. The enhancement in surface dynamics is suppressed by coating the metallic glass with a thin layer of amorphous carbon. Parallel molecular dynamics simulations on Ni<sub>80</sub>P<sub>20</sub> show a similar temperature suppression of the surface glass transition temperature and that the enhanced surface dynamics are arrested by a capping layer that chemically binds to the glass surface. Mobility in the near-surface region occurs via atomic caging and hopping, with a strong correlation between slow dynamics and high cage-breaking barriers and stringlike cooperative motion. Surface and bulk dynamics collapse together as a function of temperature rescaled by their respective glass transition temperatures.