A Chinese-led research team ‘failed to even remotely replicate the results’ of superconductivity claimed by a US team. Photo: Shutterstock Images
The results from a Chinese-led experiment have raised questions about a US research team’s claims to have created a superconducting material at room temperature, a scientific holy grail.
In a paper posted on the preprint server arXiv on Thursday, researchers from Beijing and the US state of Illinois reported that they were only able to achieve superconductivity in their experiment at -203 degrees Celsius (-333 Fahrenheit).
A pressure of 218 gigapascals was also required to reach that state. One gigapascal is equal to the pressure of 10,000 Earth atmospheres.
The results – which have not been peer reviewed and used a synthesised compound known as Lu4H23 – came a day after a University of Rochester team claimed in the journal Nature that they had been able to make a crystal superconductor at under just 1 gigapascal at 21 degrees Celsius, a pressure and temperature suitable for practical applications.
A Beijing-basedphysicistwho has studied superconductivity for more than two decades, said the University of Rochester results had not been replicated.
“In this preliminary test of the Nature paper, Chinese and US researchers obviously failed to even remotely replicate the results,” he said.
Scientists have longsought materialsthat have an electrical resistance that drops to nearly zero under certain conditions – a state known as superconductivity. The ability to transmit electricity without friction could revolutionise the efficiency ofpower grids,computer chips, high-speed trains and medical imaging.
Researchers have tried to mix hydrogen with different rare earth elements to synthesise superconductors at relatively higher temperatures. However, there had been no success using lutetium, said the physicist who did not want to be named.
The pressure needed for rare earth hydrides, or binary compounds, to reach superconductivity had usually been above 200 gigapascals – 2 million times the atmospheric pressure we live in – he said.
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Luo Huiqian from the Institute of Physics at the Chinese Academy of Sciences in Beijing, who was not involved in either experiment, said there would be a rush to try to reproduce the US results.
“Since the Nature paper said the pressure required was only 1 gigapascal, lots of laboratories around the world would try to replicate their experiment pretty quickly, even within weeks,” Luo said.
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The University of Rochester team did not give details about the preparation process of their material or its specific composition, however various possible structures could be calculated and then put to the test, Luo said.
That is what scientists did following a 2020 paper from the same team, in which the researchers had reportedly used a tiny amount of carbon, sulphur and hydrogen to achieve room temperature superconductivity.
“It turned out that no structure could achieve the superconducting temperature they had claimed,” Luo said.
The paper was so heavily criticised that it was eventually retracted by Nature last year.
Physicists in China also publicly voiced their concerns after this week’s Nature paper was published.
“Some basic facts about their study, from experiment set-up to data collection and processing, are hard for me and my colleagues to understand. If their results could be repeated, it would definitely be a revolution in the field and to the world,” Luo’s colleague, Sun Liling, told a seminar in Beijing on Friday.
