This week, scientists announced an exciting advance toward the dream of a material that can easily conduct electricity in everyday conditions. A breakthrough like this could transform almost any technology that uses electric power, opening up new possibilities for your phone, magnetic trains and future power fusion stations.
Normally, the flow of electricity encounters resistance as it moves through the wires, almost like a form of friction, and some of the energy is lost as heat. A century ago, physicists discovered materials, now called superconductors, in which electrical resistance seemingly magically disappeared. But these materials only lost their resistance at very cold temperatures, which limited practical applications. For decades, scientists have sought superconductors that operate at room temperatures.
This week’s announcement is the latest attempt in that effort, but it comes from a team facing widespread skepticism because a 2020 paper describing a superconducting material as promising but less practical was. to retreat After other scientists questioned some of the data.
The new superconductor is made of lutetium, a rare earth metal, and hydrogen with a little bit of nitrogen mixed in. It needs a pressure of 145,000 psi before it gains its superconducting prowess. This is about 10 times the pressure exerted at the bottom of the deepest ocean trenches.
But it’s also less than one-hundredth of what the 2020 result required, which was akin to the forces of destruction existing several thousand miles deep inside the Earth. This indicates that further investigations of the material could lead to a superconductor that operates at ambient room temperatures and at the typical atmospheric pressure of 14.7 psi.
“This is the beginning of a new type of material that is useful for practical applications,” Ranga P. Dias, a professor of mechanical engineering and physics at the University of Rochester in New York, told a room full of scientists on Tuesday. At a meeting of the American Physical Society in Las Vegas.
It was a complete accounting of his team’s results Published on Wednesday in Naturewhich is the same journal that published, and then retracted, the 2020 results.
The team in Rochester started with tiny, thin flakes of lutetium, a silvery-white metal that is among the rarest of the rare earth elements, and compressed it between two interlocking diamonds. Then a gas of 99 percent hydrogen and 1 percent nitrogen was pumped into the small chamber and squeezed out at high pressures. The sample was heated overnight at 150 degrees Fahrenheit, and after 24 hours, the pressure was released.
About a third of the time, the process produced the desired result: a tiny, vibrant blue crystal. “It’s not that easy to take up the nitrogen in lutetium hydride,” said Dr. Dias.
In a University of Rochester lab room used by Dr. Dias’ group, graduate student Hiranya Basan demonstrated the surprising variable property of materials during a reporter’s visit last week. As the screws were tightened to increase the pressure, the blue turned blush.
“It’s very pink,” said Dr. Dias. With higher pressures, he said, “it turns bright red.”
Shining a laser through the crystals revealed how they vibrate and unlocked information about the structure.
In another room, other members of Dr. Dias’ team were doing magnetic measurements on other crystals. As the temperatures dropped, the projected gnomes appeared in the data plotted on the computer screen, indicating the transition to a superconductor.
“That’s a direct measurement that we’re doing now,” said Dr. Dias.
In the paper, the researchers report that the pink crystals exhibited key properties of superconductors, such as zero resistance, at temperatures up to 70 degrees Fahrenheit.
“I am cautiously optimistic,” said Timothy Strobel, a scientist at the Carnegie Institution for Science in Washington who was not involved in Dr. Dias’ study. “The data in the newspaper looks great.”
“If this is real, it’s a really, really important breakthrough,” said Paul CW Chu, a professor of physics at the University of Houston who was also not involved in the research.
However, the “if” part of that sentiment revolves around Dr. Dias, who is dogged by skepticism, criticism, and even accusations by some scientists that he fabricated some of his data. The findings of the 2020 Nature paper have not been reproduced by other research groups, and critics say Dr Dias has been slow to allow others to examine his data or conduct independent analyzes of his superconductors.
The Nature editors retracted the previous paper last year over the objections of Dr. Dias and the other authors.
“I’ve lost some faith in what’s coming from that group,” said James Hamlin, a University of Florida physics professor.
However, the new paper did pass the peer review process in the same journal.
A spokeswoman for Nature said: “Withdrawal of a research paper does not automatically disqualify the author from submitting new manuscripts.” “All submitted manuscripts are considered independently on the basis of the quality and timeliness of their knowledge.”
At Tuesday’s conference in Las Vegas, so many physicists crowded into a cramped conference room that a moderator asked some to leave so they wouldn’t have to cancel the presentation. Once the room was thinned out, Dr. Dias was able to present his findings without interruption. As he thanked the crowd, the moderator lamented that they had run out of time to ask questions.
Dr. Strobel acknowledged the ongoing controversy surrounding Dr. Dias and the previous unusual claims that have yet to be reproduced.
“I don’t want to read too much into it, but there could be a pattern of behavior here,” Dr. Strobel said. “He really could be the best hyperbaric physicist in the world, about to win a Nobel Prize. Or something else is going on.”
Superconductivity was discovered by Dutch physicist Heike Kamerlingh Onnes and his team in 1911. Not only do superconductors carry electricity with zero electrical resistance, but they also possess a strange ability known as the Meissner effect that ensures that there is no magnetic field inside a material. .
The first known superconductors required temperatures a few above absolute zero, or minus 459.67 degrees Fahrenheit. In the 1980s, physicists discovered so-called high-temperature superconductors, but even those superconductors become in conditions much cooler than those we encounter in everyday use.
The standard theory explaining superconductivity predicts that hydrogen should be superconductive at higher temperatures if it can be compressed hard enough. But even the most resilient diamond breaks before it can reach stresses of this magnitude. Scientists began looking at hydrogen mixed with another element, thinking that chemical bonds might help compress the hydrogen atoms.
In 2015, Mikhail Eremets, a physicist at the Max Planck Institute for Chemistry in Mainz, Germany, reported that hydrogen sulfide—a molecule consisting of two hydrogen atoms and one sulfur atom—transformed into a superconductor at 94 degrees Fahrenheit under pressure when compressed to about 22 Mn. pounds per square inch. This was a record high temperature for a superconductor at the time.
Dr. Eremets and other scientists later discovered that lanthanum hydride—a compound containing hydrogen and lanthanum—reached a superconducting temperature of less than 10 degrees Fahrenheit under very high pressures.
In the research described in the withdrawn 2020 paper, Dr. Dias’ group used hydrogen, sulfur, and carbon. The scientists said that, through three elements, they were able to modify the electronic properties of the compound to achieve a high temperature superconductivity.
However, not everyone believed it.
Dr. Dias’ main opponent is Jorge Hirsch, a theoretical physicist at the University of California, San Diego. He focused on measurements made by Dr. Dias’ group of the response of a compound of carbon, sulfur, and hydrogen to fluctuating magnetic fields, which is evidence of the Meissner effect. The plot in the paper looked very clean, and the scientists didn’t explain how they excluded background influences in the plot.
When Dr. Dias released the underlying raw data, Dr. Hirsch said, his analysis indicated that they had been generated by a mathematical formula and could not be actually measured in an experiment. “With analogy, you don’t get analytical formulas,” said Dr. Hirsch. “You get noisy numbers.”
His complaints about Dr. Dias grew so persistent and intense that others in the field circulated a letter complaining about Dr. Hirsch’s decades of disruptive behavior.
Dr. Hirsch is a china shop showman who takes aim at BCS theory, which was devised in 1957 by three physicists—John Bardeen, Leon N. Cooper, and J. Robert Shriver—to explain how superconductivity works. In many ways, he says, BCS is a “lie,” unable to explain the Meissner effect. He came up with his own alternative explanation.
Notably, Dr. Hirsch was saying that there can be no superconductivity in any of these high-pressure materials because hydrogen cannot be a superconductor. He has gained few allies.
While Dr. Hirsch is careful to say that scientists other than Dr. Dias do not commit misconduct, he says they are fooling themselves.
“In my opinion, scraps become conclusions,” he said.
resistance and reproduction
Dr. Hamlin of the University of Florida also delved into the magnetic measurements and said it looked as if the raw data was derived from published data rather than the other way around.
Dr. Hamlin was also disturbed to find that several passages from his doctoral dissertation, which he wrote in 2007, had appeared, word for word, in Dr. Dias’ thesis.
D refuses. Dias continued criticism and says his group has provided explanations. “It just felt like background noise,” he said. “We’re trying to keep moving our science forward.”
He said he still stands by the previous findings and that the Wednesday paper used a new technique for the magnetic measurements. He said the paper went through five rounds of scrutiny by reviewers and that all the raw data behind the findings had been shared.
“It’s back in nature again,” said Dr. Dias. “So that tells you something.”
After two university investigations, Sarah Miller, a spokeswoman for the University of Rochester, said, “It has been determined that there is no evidence to support these concerns.” It also said that the university had “considered the issue of withdrawing the Nature paper in September 2022 and reached the same conclusion”.
As for a transcript of Dr. Hamlin’s doctoral dissertation, Dr. Dias said he should have included citations. “It was my fault,” said Dr. Dias.
Re-do the prepress measurements of carbon, sulfur and hydrogen of the withdrawn 2020 paper is now circulating, but even that raises questions. “They differ greatly from the original measurements,” said Dr. Strobel. “One could argue that they did not reproduce the results themselves.”
Because the new lutetium-based material is superconducting at much lower pressures, many other research groups will be able to attempt to reproduce the experiment. Dr. Dias said he wants to provide a more accurate recipe for how to make the compound and share samples, but intellectual property issues must be resolved first. He has founded a company, Unearthly Materials, which plans to turn research into profits.
Dr. Strobel said he will start working as soon as he returns from the Las Vegas conference. “We could get a result literally within a day,” he said.
Dr. Hirsch also said he expects answers to come quickly. “If this is true,” he said, “it proves my work of the past 35 years wrong.” “Which I would be very happy about, because I would know.”
Dr. Hirsch added, “But I think I’m right and it’s wrong.”
Kimberly McGee Contributed reporting from Las Vegas.
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