Turning Hydrogen Gas Into Metal

Today in relatively obscure but nonetheless meaningful scientific pursuits: two researchers at the Max-Planck Institute claim to have turned hydrogen into metal. That may seem unremarkable, but the fact is hydrogen--being an alkali metal--should exhibit the qualities of a metal under the right circumstances. Yet no one has ever coaxed the universe’s most abundant element into showing metallic qualities until now. Perhaps.

This all depends on how you qualify the term “metal.” There are some boilerplate qualifiers: Metals should conduct electricity and heat somewhat well, they should be malleable to some degree, and it makes sense that they should exist as solids under some circumstances.

But though many have tried, none have been able to make hydrogen behave like a metal under these criteria. Mikhail Erements and Ivan Troyan claim in a paper published in Nature Materials that they’ve done exactly that. First, they placed some hydrogen in an alumina-epoxy gasket and placed that within a diamond anvil cell. This allowed them to test the opacity and electrical resistance of their sample via laser and electrodes, respectively.

Then, at room temperature, they dialed the pressure up to 220 gigapascals, at which point their sample became opaque and began to show conductive properties. In the next phase of their experiment, they also dialed down the temperature to roughly -400 degrees while upping the pressure to 260 GPa. Here, electrical resistance increased by 20 percent.

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This, they claim, is hydrogen exhibiting metallic properties.

Now, other researchers are going to have to replicate the se results before they can be described as truly meaningful. And then peer reviewers are going to have to hash out whether or not these qualities truly constitute “metallic” characteristics. What is most interesting is that they made hydrogen gas conductive at room temperature by applying pressure. Materials scientists have long been looking for superconductors that can move electricity over distances without losing so much of it as waste. Perhaps hydrogen was right there staring them in the face all along.

Environment Clean Generations

PhysOrg 

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Posted in: alumina,electrodes,environment clean generations,hydrogen gas,metal,physics

Micro-explosion reveals new super-dense aluminium

Although materials scientists have theorized for years that a form of super-dense aluminum exists under the extreme pressures found inside a planet’s core, no one had ever actually seen it. Until now.

A team including researcher Arturas Vailionis of SLAC and Stanford blasted tiny bits of sapphire with a new table-top laser device that penetrates crystals and sets off micro-explosions inside them, creating powerful shock waves that compress the surrounding material. Under these extreme conditions – terapascals of pressure and temperatures of 100,000 Kelvin – warm dense matter forms, the state of matter between a solid and a plasma.

Because sapphire is a form of aluminum oxide, or alumina, researchers expected to find evidence of various phases of high-pressure alumina inside the gem. Instead, they observed minuscule amounts of a surprisingly stable, highly-compressed form of elemental aluminum called body-centered cubic aluminum.

Their results appear in yesterday’s edition of Nature Communications. The team included scientists from Australia, Japan, and the Carnegie Institution of Washington.

Vailionis, a researcher with the Geballe Laboratory for Advanced Materials and Stanford Institute for Materials & Energy Sciences, examined the interior of the sapphire and found the novel form of aluminum with a beam of X-ray light from the Advanced Photon Source at Argonne National Laboratory. The laser experiment itself was performed at Shizuoka University in Japan.

“High pressure experiments generally are done either with big equipment or with a diamond anvil cell where two diamonds are squeezing a tiny bit of material, but even diamond gives up at a certain point with those pressures,” Vailionis said. “But this very short pulse of laser light actually ionizes all the material within a very small volume over a short time and creates a plasma which is under enormous pressure and temperature” without fracturing the outer shell of the sapphire.

Of particular note, the paper says, is that the team “demonstrated that high energy density produced in a simple tabletop experiment makes it possible to form an exotic high-density material phase which could not be produced by other means.”

While scientists long have predicted that new classes of materials with unusual combinations of physical properties should exist under extreme pressure and temperature conditions, only hcp-Al, the hexagonal close-packed aluminum phase, had been observed previously.  The form made in this experiment is bcc-Al, or body-centered cubic aluminum.

Vailionis said he doesn’t expect the research to result in production of new materials in large quantities any time soon, but he believes the equipment used in the experiment offers a new strategy for synthesizing nanoscale amounts of new materials in the laboratory, and opens new possibilities for tabletop research into warm dense matter – the state of matter between a solid and a plasma. Such work could bring scientists a step closer to understanding Earth’s early history.

“Now we’re thinking about different materials we could use to recreate some of the environments that existed deep in the Earth’s core when the planet was forming,” he said.

 by "environment clean generations"

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Posted in: alumina,aluminium,biological laser,earth,materials,scientists,temperature