Scientists turned pure water into a metal, and there is footage

Pure water is a nearly perfect insulator.

Yes, naturally occurring water conducts electricity – but that’s because of the impurities it contains, which break down into free ions that allow an electrical current to flow. Pure water only becomes “metallic”—electronically conductive—at extremely high pressures, beyond what we can currently produce in a laboratory.

But as researchers first showed in 2021, it’s not just high pressures that can cause this metallicity in pure water.

By bringing pure water into contact with an electron-sharing alkali metal—in this case, an alloy of sodium and potassium—freely moving charged particles can be added, turning water metallic.

The resulting conductivity lasts only a few seconds, but is an important step towards understanding this phase of water through direct study.

“You can see the phase transition to metallic water with the naked eye!” Physicist Robert Seidel from the Helmholtz Center Berlin for Materials and Energy in Germany explained last year when the paper was published.

“The silvery sodium-potassium droplet is covered with a golden shimmer, which is very impressive.”

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Under high enough pressure, pretty much any material could theoretically become conductive.

The idea is that if you squeeze the atoms together hard enough, the outer electrons’ orbitals would start to overlap, allowing them to move. For water, that pressure is about 48 megabars — nearly 48 million times Earth’s atmospheric pressure at sea level.

While pressures in excess of this have been generated in a laboratory setting, such experiments would be unsuitable for studying metallic water. So a team of researchers led by organic chemist Pavel Jungwirth of the Czech Academy of Sciences in the Czech Republic turned their attention to alkali metals.

These substances donate their outer electrons very easily, meaning they could induce the electron-sharing properties of high-pressure pure water without the high pressures.

There’s just one problem: alkali metals react very strongly with liquid water, sometimes even to the point of exploding (there’s a really cool video below).

Drop the metal in water and you will get a kaboom.

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The research team found a very ingenious way to solve this problem. What if instead of adding the metal to the water, water was added to the metal?

In a vacuum chamber, the team first extruded a small droplet of sodium-potassium alloy, which is liquid at room temperature, from a nozzle and very carefully added a thin film of pure water by vapor deposition.

Upon contact, the electrons and metal cations (positively charged ions) flowed from the alloy into the water.

Not only did this give the water a golden glow, but it made the water conductive – just like we should see with metallically pure water under high pressure.

This was confirmed using optical reflectance spectroscopy and synchrotron X-ray photoelectron spectroscopy.

The two characteristics – the golden glow and the conductive band – occupied two different frequency ranges, allowing both to be clearly identified.

In addition to a better understanding of this phase transition here on Earth, the research could also allow for a detailed study of extreme high-pressure conditions inside large planets.

In the Solar System’s ice planets, Neptune and Uranus, for example, liquid metallic hydrogen is believed to swirl. And only on Jupiter is the pressure said to be high enough to metallize pure water.

The prospect of being able to recreate the conditions in the planetary colossus of our solar system is indeed exciting.

“Our study not only shows that metallic water can indeed be produced on Earth, but also characterizes the spectroscopic properties associated with its beautiful golden metallic luster,” Seidel said.

The study was published in Nature.

A version of this article was first published in July 2021.