Look at the snow, and you will observe one of the glowing grates, its growth depending on the surrounding conditions such as temperature and humidity. It turns out, this kind of complex self-assembly is also possible in metals, the researchers report on Dec. 9. Science.
In molten gallium, scientist Nicola Gaston and colleagues grew zinc nanostructures with symmetrical, hexagonal crystal structures. Such metallic snowflakes can be useful for catalyzing chemical and electronic reactions, says Gaston, of the MacDiarmid Institute for Advanced Materials and Nanotechnology at the University of Auckland in New Zealand.
“Self-assembly is the way nature makes nanostructures,” he says. “You’re trying to do the same thing.” Remaining aware of how small, complex metal forms could be used by artisans in fewer steps and with less energy.
The researchers chose gallium as the growth medium because of its low melting point, its ability to dissolve many other metals, and the tendency for its atoms to arrange loosely in the liquid state.
After mixing zinc into gallium, the team subjected the mixture to elevated temperatures and different pressures, and then cooled the mixture to room temperature. The only arrangement of gallium atoms was seen to soften the crystallizing zinc, so that they were found in symmetrical, hexagonal structures, like natural snowflakes and other shapes, the team found. “It’s a bit like how you arrange a fruit plate with the fruit left inside,” says Gaston.
The future may be bright for research into the applications of gallium and other cold-temperature liquid metals. “Not to take that snow metaphor too far, but” [this work] it really opens new branches for scientific discovery,” Gaston says.
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