Scientists at the University of Auckland, New Zealand, are working at the level of atoms to create something unexpected: tiny metallic snowflakes. During their research, they discovered that interactions between the atomistic structures of various metals and liquid gallium cause differently shaped crystals to emerge.
To create metallic nanocrystals, New Zealand and Australian scientists have been experimenting with gallium, a soft, silvery metal which is used in semiconductors and, unusually, liquifies at just above room temperature.
Professor Nicola Gaston and research fellow Dr. Steph Lambie, both of 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 at the University of New South Wales.
The Australian team worked in the lab with nickel, copper, zinc, tin, platinum, bismuth, silver and aluminum. Metals were dissolved in gallium at high temperatures. Once cooled, the metallic crystals emerged while the gallium remained liquid. The New Zealand team carried out simulations of molecular dynamics to explain why differently shaped crystals emerge from different metals.
What we are learning is that the structure of the liquid gallium is very important,” says Gaston. “That’s novel because we usually think of liquids as lacking structure or being only randomly structured.”
The crystals included cubes, rods, hexagonal plates, and the zinc snowflake shapes. The six-branched symmetry of zinc, with each atom surrounded by six neighbors at equivalent distances, accounts for the snowflake design.
Nanoscale structures can aid electronic manufacturing, make materials stronger yet lighter, or aid environmental clean-ups by binding to toxins.
The researchers’ results were just reported in the journal Science in the article, “Liquid metal synthesis solvents for metallic crystals”.
Image – The team’s metallic snowflake is about 100 microns across, approximately the thickness of a human hair. Courtesy of the University of Auckland.
************
For more information:
University of Auckland
