In principle, or rather, in theory, insulating materials can be made metallic by applying pressure to them. In the case of pure water, it is estimated that it requires a pressure of 48 Mbars (approximately 48 million times the Earth’s atmospheric pressure at sea level), which is beyond current experimental capabilities and can only exist indoors. of large planets or stars. However, a team of researchers from the Institute of Organic Chemistry and Biochemestry (IOCB) in Prague has achieved this effect to create a better conductor.
The scientists turned purified water into metal and conducted electricity through the liquid for a few seconds. Unfiltered water already contains salt, so it can conduct electricity. However, purified water contains only water molecules, the outermost electrons of which remain attached to those specified; therefore, they cannot flow freely in water. In theory, when enough pressure is applied to pure water, the water molecules crush and the valence shell, which is the outermost ring of electrons that surrounds each atom, overlaps. This allows electrons to flow freely between each molecule, technically turning water into a metal. And it is what they have achieved.
Could they crush the water and convert it to the metallic state without that outrageous millions of atmospheres of pressure? What would happen if we add water to the metal? This was the starting point.
To do this, they used alkali metals, which include elements such as sodium and potassium and contain only one electron in their valence shells. The alkali metals tend to “donate” this electron to other atoms when they form chemical bonds, because the “loss” of that lone electron makes the alkali metal more stable.
In the experiment, they placed a syringe filled with sodium and potassium in a vacuum chamber, squeezed small droplets from the metals, and then exposed the metal droplets to a small amount of water vapor. The water formed a 0.000003 inch (0.1 micron) film on the surface of the metal droplets and immediately electrons from the metals began to rush into the water.
Upon contact, electrons and metal cations (positively charged ions) flowed into the water from the alloy. This not only gave the water a golden glow, it made the water conductive, just as we should see in pure metallic water under high pressure.
The scientific milestone was confirmed using optical reflection spectroscopy and synchrotron X-ray photoelectron spectroscopy. The two properties, the gold luster and the conductive band, occupied two different frequency ranges, allowing them to be clearly identified.
“You can see the phase transition to metallic water with the naked eye! The silver sodium-potassium drop is covered with a golden glow, which is very impressive,” says Robert Seidel, supervisor of the experiments. “Our study not only shows that metallic water can be produced on Earth, but also characterizes the spectroscopic properties associated with its beautiful golden metallic luster.”
What applications will this technology have? We will soon know.
Reference: PE Mason et al. 2021. Spectroscopic evidence for a gold-colored metallic water solution. Nature 595, 673-676; doi: 10.1038 / s41586-021-03646-5
