small metallic snowflakes. – Zoo House News
- December 11, 2022
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Scientists in New Zealand and Australia working at the atomic level created something unexpected: tiny metallic snowflakes. Why is that important? Because coaxing individual atoms to work together in desired ways is leading to a revolution in engineering and technology about nanomaterials (and creating snowflakes is cool.) Nanostructures (a nanometer is a billionth of a meter) can aid in electronics manufacturing and make materials stronger yet lighter make , or help clean up the environment by binding to toxins.
To create metallic nanocrystals, New Zealand and Australian scientists have been experimenting with gallium, a soft, silvery metal used in semiconductors that liquefies unusually just above room temperature. Their findings have just been published in the journal Science.
Professor Nicola Gaston and research fellow Dr. Steph Lambie, both from Waipapa Taumata Rau, University of Auckland, and Dr. Krista Steenbergen of Te Herenga Waka, Victoria University of Wellington, collaborated with colleagues in Australia led by Professor Kourosh Kalantar-Zadeh of the University of New South Wales.
The Australian team worked in the lab with nickel, copper, zinc, tin, platinum, bismuth, silver and aluminum, growing metal crystals in a liquid gallium solvent. Metals were dissolved in gallium at high temperatures. After cooling, the metal crystals came out while the gallium remained liquid. The New Zealand team, part of the MacDiarmid Institute for Advanced Materials and Nanotechnology, a national center of excellence for research, ran molecular dynamics simulations to explain why differently shaped crystals are formed from different metals. (The government’s Marsden Fund supported the research.)
“What we’re learning is that the structure of liquid gallium is very important,” says Gaston. “This is novel because we normally think of liquids that have no structure or only have a random structure.” The interactions between the atomic structures of the various metals and the liquid gallium result in differently shaped crystals, the scientists showed.
Crystals included cubes, rods, hexagonal plates, and the zinc snowflake shapes. Zinc’s six-armed symmetry, in which each atom is surrounded by six equidistant neighbors, explains the snowflake design. “In contrast to top-down approaches to forming nanostructures – by cutting away material – this bottom-up approach relies on the self-assembly of atoms,” says Gaston. “This is how nature makes nanoparticles, and it’s both less wasteful and much more precise than top-down methods.” She says the research has opened up a new, uncharted avenue for metallic nanostructures. “There’s also something very cool about creating a metallic snowflake!”
Materials provided by the University of Auckland. Note: Content can be edited for style and length.