U.S. scientists create metallic hydrogen,
a possible superconductor, ending quest
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[January 27, 2017]
By Julie Steenhuysen
CHICAGO (Reuters) - U.S. scientists have
succeeded in squeezing hydrogen so intensely that it has turned into a
metal, creating an entirely new material that might be used as a highly
efficient electricity conductor at room temperatures.
The discovery, published in the journal Science on Thursday, provides
the first confirmation of a theory proposed in 1935 by physicists
Hillard Bell Huntington and Eugene Wigner that hydrogen, normally a gas,
could occur in a metallic state if exposed to extreme pressure.
Several teams have been racing to develop metallic hydrogen, which is
highly prized because of its potential as a superconductor, a material
that is extremely efficient at conducting electricity.
Currently, superconductors such as those used in a magnetic resonance
imaging, or MRI, machines must be cooled with liquid helium to keep them
at extremely low temperatures, which is costly.
“This is the holy grail of high-pressure physics,” Harvard physicist
Isaac Silvera, one of the study's authors, said in a statement. “It’s
the first-ever sample of metallic hydrogen on Earth, so when you’re
looking at it, you’re looking at something that’s never existed before.”
David Ceperley, a physics professor at the University of Illinois
Urbana-Champaign who was not involved in the research, said the
discovery, if confirmed, would end a decades-long quest to see how
hydrogen can become a metal, adding to the understanding of the most
common element in the universe.
To achieve this feat, Silvera and post-doctoral fellow Ranga Dias
squeezed a tiny hydrogen sample at more than 71.7 million pounds per
square inch (32.5 million kg per 6.5 square cm), greater than the
pressure at the center of the Earth.
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A combination of still photos taken from video shows hydrogen
magnified at different stages of compression, from gas form to
metallic, provided January 26, 2017. Photos courtesy of Isaa
Sivera/Handout via REUTERS
The scientists created this force using synthetic diamonds mounted
opposite each other in a device known as a diamond anvil cell. They
treated the diamonds with a special process to keep them from
cracking, a problem that has foiled prior experiments.
"This is just at the point when the diamonds are about to crack,"
Ceperley said. "That is why it's taken so long. Silvera had new ways
of shaping the diamonds and polishing them so they wouldn't break."
A key question is whether the pressurized hydrogen maintains its
metallic properties at room temperature, which would make it
extremely useful as a superconductor.
Both Ceperley and Silvera believe this will be the case, but it
still needs to be proven.
(Reporting by Julie Steenhuysen; Editing by Lisa Von Ahn)
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