Nebraska means flatwater in the Otoe language.
So when researcher Xiao Cheng Zeng discovered a form of ice in 1996 that contracts rather than expands when it’s frozen at extremes of subnanoscale confinement, it only made sense to name it Nebraska Ice.
“The ice we discovered in 1996 was very flat,” the University of Nebraska-Lincoln chemistry professor said.
How thin is Nebraska Ice? Think less than a billionth of a meter -- as flat as flat can be. Its technical name is Two Dimensional Bilayer Ice I.
This week, the prestigious scientific journal Proceedings of the National Academy of Science published a paper online that Zeng and research Assistant Professor Jaeil Bai wrote. It describes three discoveries they made related to Nebraska Ice.
Those discoveries include a two-dimensional ice glass formed by applying lateral pressure equivalent to 30,000 atmospheres to Nebraska Ice. The second discovery is a new two-dimensional bilayer ice form. And the third involves combining Nebraska Ice and methane to create a bilayer clathrate.
(A clathrate is a network of molecular cages in which molecules of one substance are completely enclosed in the crystal structure of another.)
Their discoveries open up numerous possibilities for improving a variety of materials, including solar cells, computer hard disks and ship bottoms.
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"Water is kind of an exquisite artwork of Mother Nature, and that's no exaggeration,” Zeng said. “I'm still amazed by its fascinating properties.”
Zeng and his research team used the NU Holland Computing Center’s supercomputers to simulate various effects on Nebraska Ice.
The two-dimensional ice glass they discovered had no long-range crystalline order in the water molecules, which instead formed a jumble of squares to pentagons. The significance, Zeng said, is that because the hydrogen bonds connecting the water molecules form a diamond pattern in normal ice -- similar to those found in carbon diamond and silicon -- this two-dimensional ice amorphous discovery can provide a window into the much more complex glassy behavior of those elements at the two-dimensional thin-film level.
That knowledge could help advance their use in solar panels, protection for computer hard disks and even the bottoms of ships, where cheap, environmentally benign carbon coatings could prevent corrosion from seawater.
Zeng and his team discovered the two-dimensional bilayer ice form after subjecting Nebraska Ice to lateral pressure equivalent to 60,000 atmospheres. The ice transformed into a square nanotube array, demonstrating a second crystalline form for Nebraska Ice.
The bilayer clathrate Zeng and his team developed by combining Nebraska Ice and methane has implications for the understanding of three-dimensional methane hydrates that are buried in seabeds around the world. Those methane hydrates could provide as much as 20,000 terawatt-years of energy, compared to the 1,000 terawatt-years estimated to remain in conventional oil and gas.
The discovery also could shed light on gas clathrates that form in deepwater oil and gas pipelines and block the flow. The bilayer clathrate could offer insights into the properties of more complex three-dimensional gas hydrate materials and help researchers learn to manipulate those gas hydrates to prevent pipeline blockages, Zeng said.
"Each discovery gives us new excitement, but it also raises more questions,” he said. “That's why water fascinates me."