Atomistics of pre-nucleation layering of liquid metals at the interface with poor nucleants

Liquid layering at heterogeneous solid/liquid interfaces is a general phenomenon, which provides structural templates for nucleation of crystalline phases on potent nucleants. However, its efficacy near poor nucleants is incompletely understood. Here we use a combination of X-ray crystal truncation...

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Bibliographic Details
Published in:Communications chemistry 2019-01, Vol.2 (1), Article 1
Main Authors: Ma, Sida, Brown, Adam J., Yan, Rui, Davidchack, Ruslan L., Howes, Paul B., Nicklin, Chris, Zhai, Qijie, Jing, Tao, Dong, Hongbiao
Format: Article
Language:English
Subjects:
639/301/1023/1026
639/301/1034/1035
639/301/930/12
Aluminum
Chemistry
Chemistry and Materials Science
Chemistry/Food Science
Crystal structure
Crystallinity
Crystals
Interfaces
Layering
Liquid metals
Molecular dynamics
Nucleation
Sapphire
Substrates
Surface structure
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Summary:Liquid layering at heterogeneous solid/liquid interfaces is a general phenomenon, which provides structural templates for nucleation of crystalline phases on potent nucleants. However, its efficacy near poor nucleants is incompletely understood. Here we use a combination of X-ray crystal truncation rod analysis and ab initio molecular dynamics to probe the pre-nucleation liquid layering at the sapphire–aluminium solid/liquid interface. At the sapphire side, a ~1.6 aluminium-terminated structure develops, and at the liquid side, two pre-nucleation layers emerge at 950 K. No more pre-nucleation layer forms with decreasing temperature indicating that nucleation of crystalline aluminium through layer-by-layer atomic adsorption of liquid atoms is not favoured. Instead, the appearance of stochastically-formed nuclei near the substrate is supported by our experiments. Nucleation on poor nucleants is dominated by the stochastic nucleation events which are substantially influenced by the pre-nucleation layers that determine the surface structure in contact with the nuclei. Liquid layering at heterogeneous surfaces is a general phenomenon but is poorly understood. Here the authors probe pre-nucleation liquid layering at the sapphire–Al solid/liquid interface using a combination of in situ X-ray crystal truncation rod analysis and ab-initio molecular dynamics simulations.
ISSN:2399-3669
2399-3669
DOI:10.1038/s42004-018-0104-1