Scientists have turned pure water into metal, and there are pictures

Scientists have turned pure water into metal, and there are pictures

Pure water is an almost perfect insulator.

Yes, the water found in nature conducts electricity, but that’s because of the impurities it contains, which dissolve into free ions that allow an electric current to flow. Pure water only becomes “metallic” – electronically conductive – at extremely high pressures, beyond our current laboratory production capabilities.

But, as researchers first demonstrated in 2021, it’s not just high pressures that can induce 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 – free-moving charged particles can be added, turning the water into metal.

The resulting conductivity only lasts a few seconds, but it is an important step in being able to understand this phase of water by studying it directly.

“You can see the phase transition to metallic water with the naked eye!” Physicist Robert Seidel of Helmholtz-Zentrum Berlin für Materialien und Energie in Germany explained last year when the paper was published.

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

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Under high enough pressures, just about any material could theoretically become conductive.

The idea is that if you squeeze the atoms together enough, the orbitals of the outer electrons will start to overlap, allowing them to move. For water, this pressure is about 48 megabars, or just under 48 million times the Earth’s atmospheric pressure at sea level.

Although pressures exceeding this have been generated in a laboratory environment, such experiments would be unsuitable for the study of metallic water. So a team of researchers led by organic chemist Pavel Jungwirth from the Czech Academy of Sciences in the Czech Republic turned to alkali metals.

These substances release their outer electrons very easily, which means that they could induce the electron-sharing properties of highly pressurized pure water without the high pressures.

There’s only one problem: Alkali metals are very reactive with liquid water, sometimes even to the point of explosion (there’s a really cool video below).

Drop the metal into the water and you’ll get a kaboom.

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

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

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

Not only did this give the water a golden sheen, it made it conductive – just as we should see in high pressure metallic pure water.

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

The two properties – the golden shine and the conductive stripe – occupied two different frequency ranges, which made it possible to clearly identify them both.

In addition to giving us a better understanding of this phase transition here on Earth, the research could also allow in-depth 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 thought to swirl around. And only Jupiter in which the pressures are thought to be high enough to metallize pure water.

The prospect of being able to replicate the conditions inside 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 research has been published in Nature.

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

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