• Liquid metals, surface patterns, and the

    From ScienceDaily@1:317/3 to All on Fri Feb 4 21:30:46 2022
    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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