Experiment offers glimpse at how to make hydrogen metallic

hydrogen squeezing experiment

TIGHT SQUEEZE  Inside the red cylinder, two diamonds gradually compress hydrogen to pressures as high as about 3.8 million times atmospheric pressure at sea level. Laser light probes the crushed hydrogen.

Philip Dalladay-Simpson and Eugene Gregoryanz

A crushing squeeze between diamonds has pushed hydrogen to the brink of morphing into a metal. Scientists in Scotland and China discovered a new solid phase of hydrogen after subjecting the universe’s most abundant element to pressures that dwarf the water pressure at the seafloor. The researchers speculate that slightly more pressure may coax hydrogen to take on a solid, metallic form.

In nature, pairs of hydrogen atoms bond tightly to form the molecule H2. But with enough pressure, the bonds should break, allowing electrons to flow freely past individual atoms as they do in metals.

The researchers found that at pressures between about 3.2 million and 3.8 million times as high as the atmospheric pressure at sea level, hydrogen seemed to exist as a part-molecular, part-atomic layer cake. As little as a several percent boost in pressure could coax the rest of the sample to turn metallic, the researchers suggest January 7 in Nature.

Metallic hydrogen could have special properties, such as the ability to conduct electric current with no resistance at room temperature.

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