Diamond anvil

The first superconductor at room temperature could trigger an energy revolution

By Leah Crane

The compression of elements between two diamonds creates the extraordinary pressures required for superconductivity

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Room temperature superconductivity has been a buzzword in materials science for decades, but now it can finally become a reality and have the potential to revolutionize the way we use electricity.

A tremendous amount of the energy we produce is wasted due to the electrical resistance that creates heat. However, in a superconducting material, electric current can flow without resistance, which means that these losses do not occur.

This property has made such materials extremely desirable, but until now they have required very low temperatures and extremely high pressures to work.

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"If you had a room temperature superconductor that you could use at atmospheric pressure, you could envision a number of large-scale applications," says M. Brian Maple of the University of California at San Diego. "I'm just afraid that materials science could be so difficult that you might not find a superconductor that works well enough for these applications."

Now Ranga Dias of the University of Rochester, New York, and his colleagues have solved half of that problem. The team made a superconductor by crushing carbon, sulfur, and hydrogen between two diamonds at a pressure about 70 percent of the pressure at the center of the earth and at a temperature of about 15 ° C. This is the highest temperature at which superconductivity has ever been measured, and the first that can reasonably be called room temperature.

Solid metallic hydrogen is expected to be superconducting on its own, but it is incredibly difficult to manufacture because it requires exceptional pressure. The researchers found that adding carbon and sulfur to the hydrogen causes it to act as if it is at a higher pressure than it actually is.

“Suppose you are in a room and have four walls. One way to compress is to bring the walls closer and closer. However, you can keep the room size the same and let 10 people in the room feel squeezed, ”says Dias. In this experiment, adding carbon and sulfur to the hydrogen is like adding more people to the room: it is used to chemically precompress the hydrogen.

When Dias and his team found that the electrical resistance of their material went to zero at 15 ° C, they ran several other tests to confirm that it was really superconducting, e.g. B. to make sure it blocks magnetic fields. "These are very thorough experiments that basically got to the point. When you look at the data, it's breathtaking to see," says Shanti Deemyad of the University of Utah. "That will shake the field."

However, questions still remain. For example, although we know that the superconducting material is made up of carbon, sulfur, and hydrogen, we don't know how these elements are connected. "In this type of research, it's not uncommon to do an experiment without knowing the structure," says Eva Zurek of the State University of New York in Buffalo. More theoretical work will be needed to compare the behavior of the material with models of various compounds and find out what exactly it is, she says.

Dias and his colleagues are now working on producing their material at lower pressures. "Take diamond: it's a high pressure form of carbon, but nowadays you can grow it in a laboratory using chemical deposition techniques," says Dias. "It used to require a lot of pressure, now we can build it – with superconductors we can possibly do something similar."

The fact that this compound contains three different elements while other superconductors have tended to contain only one or two makes it more adjustable which, according to Dias, will help it work at lower pressures.

If this can be achieved, this material could be used in applications ranging from quantum computers to building better MRI machines to drastically reducing the amount of energy wasted in transmitting electricity. “If we could manufacture superconducting wires that we don't have to cool, we could in principle replace the entire power grid,” says Zurek. "That would be a real revolution."

Journal reference: Nature, DOI: 10.1038 / s41586-020-2801-z

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