By Scott Hamilton
Senior Expert Emerging Technologies
In the last week I learned about two new forms of water. I already knew about the four states of water that most people are familiar with – ice, liquid, steam and plasma. Plasma is one that you may not have heard about; it is basically super-heated steam that has new characteristics. As it turns out, there are now 18 forms of water, most which classify as ice because they are unique solid forms of ice. If you want to learn about all the special forms of ice, a great place to look is https://en.wikipedia.org/wiki/Ice.
Superionic ice was predicted 30 years ago but was not actually seen until May 2019. Marious Millot and Federica Coppari of Lawrence Livermore National Lab fired one of the world’s most powerful lasers at a droplet of water. The laser at the Laboratory for Laser Energetics in Brighton, N.Y., struck the water droplet, causing a shock wave that raised the pressure in the droplet to millions of atmospheres and thousands of degrees. They were monitoring the state of the water with high resolution X-rays to give the world a first glimpse at water under the extreme conditions.
The results of the experiment were surprising to me, as I am sure they are to you, but it did not surprise Coppari and Millot. They were expecting exactly what they saw, because computer models predicted the outcome about thirty years ago. It was only recently the technology became available to perform the experiment and confirm the existence of the predicted ice xviii. Instead of becoming a superheated liquid or gas, it formed an ice – a very high temperature ice that only lasted less than a second before cooling and becoming a vapor. The superionic ice xviii was black, hot and dense. A regular ice cube from your freezer floats in water because it is less dense, meaning the same volume of ice weighs less than water. Ice xviii weighs much more than liquid water and nearly four times more than the ice in your freezer, but it would boil your tea instantly instead of making it cold.
Even though ice xviii was not seen before this experiment, scientist believe it is the most abundant form of water in the universe. The structure of ice xviii answers several questions about the core of ice giant planets Uranus and Neptune. Their cores are not a molten center as originally thought, but rather a superheated solid like ice xviii. Including the normal hexagonal arrangement of water molecules in common ice, scientists had already discovered 18 distinct architectures of ice. Superionic ice can now officially claim the mantle of ice xviii, the new crystal, but with a twist – all previously known water ices are made with the water molecules intact, but the new ice isn’t normal. It exists in a state of limbo, part solid, a cubic oxygen lattice, and part liquid, the hydrogen atoms flowing free like a liquid spilling through the oxygen cage. The discovery vindicates computer predictions, and as a result, helps material physicists craft future substances with greater confidence.
The other new form of water is a metallic liquid, meaning it is capable of conducting electricity. Unfiltered water can already conduct electricity, a fact that is used in water purification systems to measure the purity of the water. But 100 percent pure water acts like an insulator and will not conduct electricity. Theoretically if enough pressure were applied to water, the molecules would be forced to overlap in a way that allow the electrons to flow freely between molecules, turning the water into a metal. The study by Pavel Jungwirth, Czech Academy of Sciences in Prague, suggested this pressure would need to be about 220 million psi. For this reason, geophysicists suspect that such water-turned-metal might exist at the core of huge planets like Jupiter, Neptune and Uranus. Jungwirth decided instead of trying high pressure like the ice xviii experiment, to attempt the transition through chemical reactions with alkali metals sodium and potassium. These metals react violently with water and cause an explosion, Jungwirth and his team decided if they could somehow avoid the explosion, the water could just borrow the electrons from the reaction and turn the water metallic. They were successful in the experiment and made the world’s first metallic water on July 28, 2021.
Until next week, stay safe and learn something new.
Scott Hamilton is a Senior Expert Emerging Technologies at ATOS and can be reached with questions and comments via email to firstname.lastname@example.org or through his website at https://www.techshepherd.org.