Liquid metals, surface patterns, and the romance of the three kingdoms


Date:
February 4, 2022
Source:
ARC Centre of Excellence in Future Low-Energy Electronics
Technologies
Summary:
Diverging and converging patterns forming on the surface of
solidifying liquid metals resemble plotlines in a complex historical
novel, in a new international study. The cyclic patterns observed
are rare, and had not been observed in solidification structures
prior to this. Better understanding and control of fundamental phase
transitions and pattern formation could see future liquid metal
applications in plasmonic sensing and high-efficiency electronics
and optics.



FULL STORY ==========================================================================
"The long divided, must unite; long united, must divide. Thus it has
ever been."

==========================================================================
The opening lines of the great Chinese historical novelRomance of the
Three Kingdoms condense its complex and spectacular stories into a
coherent pattern, that is, power blocs divide and unite cyclically in
turbulent battle years.

A good philosophy or theorem has general implications. Now, published
in the journal Nature Synthesis, scientists from Australia, New Zealand,
and the US reported a new type of solidification patterns that resembles
the plots in the Chinese classic, but this time appearing on the surface
of solidifying liquid metals.

The team dissolved a small amount of metals such as silver (Ag) in
low-melting- point solvent metals such as gallium (Ga), and investigated
how the metallic components interact and separate to form patterns when
the metallic liquid mixtures (alloys) solidify.

The researchers found that a single silver-gallium system can produce
distinct patterns such as particles or bundle-like structures of a
Ag2Ga compound.

The individual Ag2Ga structures that build the patterns are small, with micrometre or nanometre thicknesses, tens or hundreds of times less than
a human hair.



==========================================================================
Most surprisingly, the researchers observed that the patterns divide
and unite in a repeated manner. "The first time I saw such cyclic divergent-convergent patterns, it immediately reminded me of the famous
opening lines of the Romance of the Three Kingdoms," said Dr Jianbo Tang
from University of New South Wales (UNSW, Australia), who is the first
author of the study.

Pattern formation is a fundamental yet ubiquitous phenomenon which has interested and inspired scientists for a long time. Some pattern types
are more common than others.

Among all the diverse patterning behaviours, divergent pattern
formation, or bifurcation, is frequently seen in nature because
this particular arrangement generally favours energy conversion or distribution. "I.e. it's the 'easiest' path," explains Dr Tang. River
networks, tree branches, lightning pathways, and vascular systems are
all examples of bifurcation.

In comparison, convergent pattern growth, or inverse bifurcation,
is encountered less frequently as it is contrary to the energetically favourable bifurcation.

The strange cyclic divergent and convergent growth, called oscillatory bifurcation, is rare and has not been observed in solidification
structures prior to the new published work.

Despite this, the researchers observed oscillatory bifurcation patterns
on the surface of several liquid alloys after solidification, which
suggests that this counter-intuitive behaviour is quite general for solidification patterns forming on the surface of liquid metals.

Analogous to the dramatized novel where the turbulent forces between
and within a large number of power blocs drive those groups to divide
and unite, the team found that it is also the instability of the liquid
metal surface that underlies the emergence of the exotic oscillatory bifurcation patterns.

"Surface pattern formation of liquid metal alloys is a new but exciting
topic.

The surface or interfacial nature of the process enables us to better understand and control fundamental phase transition and pattern
formation." Dr.

Tang added, "We will continue our work on designing crystalline surface patterns and structures using liquid metals to enable cutting-edge
applications such as plasmonic sensing, high-efficiency electronics
and optics, and high- precision spectroscopic." In addition to support
from the Australian Research Council (Laureate Fellowship, Centres of Excellence, and Discovery programs) this work was also supported by computational resources provided by the Australian Government through
the National Computational Infrastructure facility and the Pawsey
Supercomputer Centre.

========================================================================== Story Source: Materials provided by ARC_Centre_of_Excellence_in_Future_Low-Energy_Electronics
Technologies. Note: Content may be edited for style and length.


========================================================================== Related Multimedia:
* Surface_patterns ========================================================================== Journal Reference:
1. Jianbo Tang, Stephanie Lambie, Nastaran Meftahi, Andrew J.

Christofferson, Jiong Yang, Jialuo Han, Md. Arifur Rahim, Mohannad
Mayyas, Mohammad B. Ghasemian, Francois-Marie Allioux, Zhenbang
Cao, Torben Daeneke, Chris F. McConville, Krista G. Steenbergen,
Richard B.

Kaner, Salvy P. Russo, Nicola Gaston, Kourosh
Kalantar-Zadeh. Oscillatory bifurcation patterns initiated by
seeded surface solidification of liquid metals. Nature Synthesis,
2022; DOI: 10.1038/s44160-021-00020-1 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220204093115.htm

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