Quirks & Quarks

Discovery of near room temperature superconductors could bring floating trains and more

A superconductor can transmit electricity with no loss of energy

A superconductor can transmit electricity with no loss of energy

Previous superconductors, like the one seen in this photo, needed to be cooled to very low temperatures. Now two different teams say they've attained near room temperature superconductors. (BERTRAND GUAY/AFP/Getty Images)
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Two teams — independent of each other — say they've attained what is widely considered to be one of the holy grails of physics: a near room temperature superconductor. 

This technology could hold the key to nuclear fusion, magnetically levitating passenger trains, or even a superconducting supercolliders.

A superconductor can transmit electricity with no loss of energy. Currently we throw away up to about ten per cent of our energy generation in transmission losses from resistance in the power lines. But superconductors offer no resistance at all. 

"We could in theory replace all of the electrical wires in our houses and in the electrical power lines with these superconductors and save a lot of energy," said Dr. Eva Zurek, a Canadian professor of theoretical chemistry at the University at Buffalo, in conversation with Quirks & Quarks host Bob McDonald. 

The lead scientist in one of these groups, Dr. Maddury Somayazulu, an associate research professor of high-pressure physics at George Washington University, described their discovery in a statement as a "paradigm-changing moment in the history of science."

Two near room temperature superconductors 

All superconducting materials that scientists have discovered before this need to be cooled to well below -100 C to work, which is not very practical for most uses.

The team from The George Washington University, whose findings were published this week in the journal Physical Review Letters, describe finding a superconducting critical temperature of about minus 13 degrees Celsius at 185 gigapascals. 

"185 gigapascals is about half the pressure that is in the centre of the Earth," said Zurek. 

The second team from Max Planck Institute for Chemistry in Germany, whose findings were published in the preprint archive arXiv.org, claims to have measured superconductivity at about minus 23 degrees Celsius at 170 gigapascals. 

While both temperatures — minus 23 C and minus 13 C — are closer to the what a Canadian winter feels like than a room temperature superconductor, the U.S. team also claims that in subsequent experiments, they managed to reach 7 C at 200 gigapascals. 

"The two teams have claimed that they have made a new hydride of lanthanum, probably LaH10. Such a material would not be stable without pressure," said Zurek. The way they attained those extremely high pressures was by squeezing the material between two diamond anvil cells. 

What remains to be proven

"The resistance drops to zero are not sufficient to prove without a doubt that it is a superconductor," said Zurek. "There are a few other experiments that must be carried out."

One experiment is they need to detect something called the Meissner effect. 

Two teams have now reported they've attained near room temperature superconductors, although neither team has yet been able to prove the Meissner effect, as seen in this photo of a very low temperature superconductor. (Pongkaew / Wikimedia)

"If you have these maglev trains, they levitate on the superconductors. And the reason for that is the superconductor expels the magnetic field. And so that's known as the Meissner effect. And they need to show that in order to prove that it is superconducting. The Meissner effect has not been proven in this case. However I know that both groups are working on it."

Dawn of a new superconducting era? 

The samples both teams used are very tiny and under enormous pressure, so they're not yet ready for practical use. 

"[A] diamond itself is synthesized under pressure and the carbon-carbon bonds are very strong," said Zurek. "So when you release the pressure, the diamond does not convert back into graphite. So it's considered something called a 'metastable material.' If we could potentially make some sort of metastable system that would remain stable once you release the pressure, that would be amazing."

This is definitely materials by design, showing that it works.- Dr. Eva Zurek, University at Buffalo

Creating a compound that can superconduct at a reasonable temperature without having pressure exerted on it is still likely a long way off. Still Zurek, who as a theoretical chemist works to computationally predicts these types of materials, says she's excited about these developments. 

"All of the discoveries in superconductivity prior to to these have been completely serendipitous — people measure random materials and find that they're superconducting," said Zurek. "And the lanthanum hydride superconductor, that was actually theoretically predicted before it was synthesized. And because you can theoretically predict it, it basically doesn't waste as much time. This is definitely materials by design, showing that it works."

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