Magical materials that can easily conduct electricity at room temperature have the potential to recover energy lost through electrical resistance, open up new technological possibilities, and transform civilizations.
But such claims about room-temperature superconductors, published in the prestigious journal Nature in March, raised questions and some suspected that the results were fabricated.
Now, however, a group of researchers at the University of Illinois at Chicago reports that they have confirmed an important measurement: a clear loss of electrical resistance.
While the results do not prove the material is a room-temperature superconductor, it may motivate other scientists to investigate further.
Ranga P. Diaz, a professor of mechanical engineering and physics at the University of Rochester, New York, and the lead author of the original study, said the material appears to be a superconductor at temperatures of 70 degrees Fahrenheit (much warmer). reported that it looks like It outperforms other superconductors when squeezed at a pressure of 145,000 pounds per square inch, about ten times the pressure experienced at the bottom of the ocean’s deepest trenches.
The high pressure means the material is unlikely to be of practical use, but if the discovery is true, it points the way to other superconductors that truly function in everyday situations. there is a possibility.
The claim was met with skepticism, as some scientific controversy swirled around Dr. Diaz, and other scientists who tried to replicate the results failed to detect any signs of superconductivity.
Dr. Diaz founded Unearthly Materials to commercialize his research and has raised $16.5 million from investors to date.
new measurements revealed in preprinted paper The paper, posted this month, is the work of a team led by Russell J. Hemley, professor of physical chemistry at the University of Illinois at Chicago. Hemley declined to comment because the paper has not yet been accepted by a scientific journal.
Nevertheless, he is highly regarded in the field, and his report may lead to a more positive review of Dr. Diaz’s superconducting claims.
“This might convince some people,” says James J. Hamlin, a professor of physics at the University of Florida who has been a persistent critic of Diaz’s work. “It makes me wonder if it has something to do with it.”
Dr. Diaz’s material is made of lutetium, a silver-white rare earth metal, with hydrogen and a small amount of nitrogen. Dr. Hemley’s lab used samples provided by Dr. Diaz to perform independent measurements of the electrical resistance of the material as it cooled under high pressure.
Dr. Hemley and his colleagues observed a sharp drop in the material’s electrical resistance. These occurred at temperatures up to 37 degrees Fahrenheit, about 30 degrees lower than Diaz described, but would still be warmer than other superconductors. The transition temperature varied depending on how hard the material was squeezed.
“They performed electrical resistance measurements to confirm our results,” Dr. Diaz said in an interview. “It shows a pressure dependence of the transition temperature, which is in very good agreement with what we reported in our Nature paper in March.”
Dr. Hemley’s measurements provide no evidence of superconductivity. This material may not be a superconductor, but simply a very good conductor.
The report did not include measurements to determine whether there was zero magnetic field inside. This phenomenon, known as the Meissner effect, is considered the definitive proof of superconductors.
Some of Dr. Diaz’s early papers have caused heated debate. Critics, including Dr. Hamlin, say that it sometimes omits important details about how the experimental data were processed.journal Nature retracted even the paper The paper, published in 2020, claimed to be a former superconductor, despite the objections of Dr. Diaz and other authors that the discovery is still valid.
Dr. Hamlin also points to Dr. Diaz’s line of work. PhD thesis at Washington State University, 2013 it was CopiedIt is an almost verbatim excerpt from the work of other scientists, including Dr. Hamlin’s own doctoral dissertation.
Dr. Diaz acknowledged copying someone else’s work in the paper and said the citation should have been included. He denies scientific misconduct in his previous papers.
“I have never knowingly been involved in the deliberate plagiarism of anyone’s scientific work,” Dr. Diaz said. “It was an oversight.”
The findings of Dr. Hemley’s team claim that Dr. Diaz did indeed discover something new in the substance lutetium-hydrogen-nitrogen.
Lilia Boeri, professor of physics at the University of Rome Sapienza, said it wasn’t a repeat of a scientific scandal 20 years ago when researcher J. Hendrik Schoen of Bell Laboratories in New Jersey was found to have committed a scientific scandal. said it was clear. He fabricated data to claim a series of breakthrough discoveries.
“It’s a completely different story in the sense that he certainly produced something and measured something,” Dr. Boeri said of Diaz.
But she added. “Whether this is a sign of superconductivity or simply that he discovered some interesting electron transport is completely unknown.”
In recent years, materials known as hydrides have shown promise in the search for superconductors that operate at higher temperatures, but so far they all require crushing pressures. Diaz said it was the hydrides that led to the lutetium-hydrogen-nitrogen mixture.
But Dr. Boeri said other hydrides fit the standard theory of superconductivity, but Dr. Diaz’s material does not.
previous paperDr. Hemley, along with Adam Denchfield, a physics graduate student at the University of Illinois at Chicago, and Hyowon Park, an assistant professor of physics at the same university, are trying to explain why, and the researchers say that electrons He says he overlooks the subtleties of engineering. The structure of lutetium-hydrogen-nitrogen compounds may provide an explanation for the higher superconducting temperature.
They propose that the elements of Dr. Diaz’s material could be composed of different structures. The superconducting current flows through a small amount of different structures within the compound, although the most common structure may be responsible for the color change and other properties observed. This may explain why not all samples made in Dr. Diaz’s lab are superconducting.
But Dr. Boeri is unfazed.
“The theoretical arguments are quite strange,” she says. Dr. Boeri said materials with high superconducting temperatures require a very rigid lattice structure, which the material does not have, and the paper does not discuss this issue.
Eva Zurek, a professor of chemistry at the University of Buffalo who has worked with both Dr. Hemley and Dr. Diaz on other projects, was initially skeptical, but has now partially changed her mind.
Numerical simulations of superconductors include simplifications to make the calculations. Dr. Hemley’s paper argued that the calculations should be performed somewhat differently, and Dr. Zurek’s group attempted to modify them and arrived at the same answer.
“It turns out it’s not impossible,” Dr. Zurek said. “We’re not dismissing that possibility right away, so let’s be that way.”
