How do you like your ice? Cold and icy might be your bland refrain.
But scientists can rattle off no fewer than 18 different kinds of ice, each categorized as an architecture, based on its specific arrangement of water molecules. So the ice that we use to chill our drinks is designated either Ice Ih or Ice Ic.
After that, architectures — dubbed Ice II all the way to Ice XVII — get increasingly strange, with most of them being created in laboratories through the application of different pressures and temperatures.
But now, there's a new ice on the block. At least, an ice newly known to us — even if it may be very ancient and very common.
Researchers at the Lawrence Livermore National Laboratory in California blasted a single droplet of water with a laser to "flash freeze" it into a superionic state.
Their findings, published this month in the journal Nature, confirm the existence of Ice XVIII, or more descriptively, superionic ice.
This ice isn't like the others
Okay, so there's not actually much to behold here — since superionic ice is very black and very, very hot. In its brief existence, this ice produced temperatures between 1,650 and 2,760 degrees Celsius, which is about half as hot as the surface of the sun. But on a molecular level, it's strikingly different from its peers.
Ice XVIII doesn't have the usual setup of one oxygen atom coupled with two hydrogens. In fact, its water molecules are essentially smashed, allowing it to exist as a semi-solid, semi-liquid material.
"We wanted to determine the atomic structure of superionic water," Federica Coppari, co-lead author of the paper noted in the release. "But given the extreme conditions at which this elusive state of matter is predicted to be stable, compressing water to such pressures and temperatures and simultaneously taking snapshots of the atomic structure was an extremely difficult task, which required an innovative experimental design."
For their experiments, conducted at New York's Laboratory for Laser Energetics, scientists bombarded a water droplet with increasingly more intense laser beams. The resulting shockwaves compressed the water to anywhere from 1 to 4 million times Earth's atmospheric pressure. The water also hit temperatures ranging from 3,000 to 5,000 degrees Fahrenheit.
As you might expect under those extremes, the water droplet gave up the ghost — and became the bizarre, super-hot crystal that would be called Ice XVIII.
Ice, ice ... maybe? The thing is, superionic ice may be so strange, scientists aren't even sure it's water at all.
"It's really a new state of matter, which is rather spectacular," physicist Livia Bove tells Wired.
In fact, the video below, also created by Millot, Coppari, Kowaluk of the LLNL, is a computer simulation of the new superionic water ice phase, illustrating the random, liquid-like motion of the hydrogen ions (gray, with a few highlighted in red) within a cubic lattice of oxygen ions (blue). What you're seeing is, in effect water behaving as both a solid and a liquid at the same time.
Why superionic ice matters
The existence of superionic ice has long been theorized, but until it was created recently in a lab, no one has actually seen it. But that, too, may not be technically true. We may have been staring at it for ages — in the form of Uranus and Neptune.
Those ice giants of our solar system know a thing or two about extreme pressure and temperature. The water they contain may undergo a similar process of molecule-smashing. In fact, scientists suggest the planets' interiors may be crammed full of superionic ice.
Scientists have long wondered what lies beneath the gaseous shrouds surrounding Neptune and Uranus. Few imagined a solid core.
If those titans boast superionic cores, not only would they represent far more water in our solar system than we ever imagined, but also whet our appetites for giving other icy exoplanets a closer look.
"I used to always make jokes that there's no way the interiors of Uranus and Neptune are actually solid," physicist Sabine Stanley of Johns Hopkins University tells Wired. "But now it turns out they might actually be.