Frosty cubes from our freezers, fine snows, and even Elsa's "Let It Go" creations--those are just some of the 17 possible types of ice!
And now, there might be an 18th type.
A "normal ice" has a solid crystal form with hexagonal structure. This is formed when the water freeze under ambient pressure. Meanwhile, when such cools at atmospheric pressure or higher, they get squeezed into denser ones. And when it drops below, the water crystal becomes less-dense.
There are only two known types of low-density ice today: space fullerenes, which are 80 per cent of the density of normal ice; and zeolitic ices which are 50 and 90 per cent the density of normal ice. Like an icy candy floss!
But are there other lighter ones?
“We just found there are two low-density ices very recently, but we did not know about the breadth of the world at all. We need a map of this New World in order to explore it experimentally,” says Masakazu Matsumoto at Okayama University in Japan.
Hence, they utilized the existing zeolitic ice and restructured them to become lighter. Simulating more than 300 different nanoscale structures together with their stability, a new type of porous, lightweight “aeroice” was discovered. The aerogel of ice. These were found to be stable at near 0 Kelvin, and loses its stability more and more as the temperature rises.
Matsumoto even believes there could be more--much lighter ices. But creating ultralow-density ones can be a huge challenge as it requires extremely low pressure and low temperature.
Christoph Salzmann at University College London says this work will help us understand how water molecules behave under extreme conditions. “It gives us something to chase after. Now that these guys have predicted all these amazing structures, the next step for us would be to actually go and make them,” he says.
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