The popularity of the ChatGPT large model has just declined, and scientists from South Korea, the United States and China have stirred up a new round of controversy and attention in the scientific and technological circles over the topic of “room temperature superconductivity” technology.
On August 1, Beijing time, the Lawrence Berkeley National Laboratory (LBNL) team in the United States submitted a paper on the arXiv platform titled “The Origin of Related Isolated Flat Bands in Copper-Substituted Lead Phosphate Apatite” and used supercomputer simulations to discover copper When replacing lead in apatite, it causes structural distortion. The results support the experimental results of the Korean scientific research team that discovered the room temperature superconductor LK-99 crystal a week ago. The lattice parameters differed by 1% from the previous experimental results.
This is the world’s first relevant paper to prove the feasibility of the theory of “normal temperature and normal pressure superconductors”. It provides new directions and inspirations for the technical research of “room temperature superconducting” materials, and is expected to promote the application development of the room temperature superconducting industry with a scale of hundreds of billions.
A week ago, a South Korean scientific research team claimed to have achieved “room temperature superconductivity” using the copper-doped lead apatite material LK-99 crystal. There was a lot of controversy in the academic community, and multiple teams carried out “reproduction frenzy” to prove it. Fake.
In addition to the American team, on the afternoon of August 1, a team from the School of Materials at Huazhong University of Science and Technology in China also successfully verified for the first time the synthesis of LK-99 crystals that can be magnetically levitated. Russian scientist Iris Alexandra also successfully reproduced it, but the Indian National Physical Laboratory team Both reproductions failed, and another team from the Institute of Physics, Chinese Academy of Sciences and Huazhong University of Science and Technology achieved an unconfirmed partial reproduction.
As early as 2020, “Science” magazine published an article saying, “Finally, room temperature superconductivity has been achieved.” However, before, Diaz’s “room temperature superconductivity” experiment in the United States could not be reproduced, and the overall failure was a failure.
It is worth mentioning that on August 2, it was reported that Sukbae Lee, the author of South Korea’s “Room Temperature Superconductivity” paper, said that the paper had flaws and that one member of the team, Professor Young-Wan Kwon, had not Other authors have given permission to publish without permission, and the team is currently requesting arXiv to remove the paper.
Interestingly, Sam Altman, the father of ChatGPT and CEO of OpenAI, directly complained: A month ago, everyone was paying attention to the social software battle between Elon Musk and Mark Zuckerberg, but now, people are worried about the possibility of Be amazed by having a true room-temperature superconductor.
Affected by this news, capital market-related concept stocks seem to have “boiled” in advance. On August 1, in the U.S. stock market, American Superconducting, a wind turbine electronic control system company, once rose by more than 100%; while domestic superconducting stocks Yongding, Fasten, and Baili Electric rose by 20% and hit their daily limit.
After 192 hours of “room temperature superconductivity” controversy and reversal
According to public information, the full name of room temperature superconductor is superconductivity, also known as room temperature superconductor, which refers to materials that can have superconductivity at temperatures higher than 0 degrees Celsius. One of the characteristics of superconductors is “zero resistance”, that is, when the current passes, there is no loss due to any resistance. Therefore, this is a revolutionary material.
For many years, finding a superconductor that can be used without extremely low temperatures or extremely high pressures has been a big dream of the superconducting community.
In 1908, Dutch physicist Heike Kamerlingh Onnes successfully liquefied helium and obtained a low temperature of 4.2K (about -269 degrees Celsius) close to absolute zero. In 1911, Onnes and others found that when the mercury was cooled with liquid nitrogen, the resistance of mercury dropped sharply to disappear when the temperature dropped to about 4.2K, and it was completely conductive. In 1913, Onnes found that tin and lead were also the same as mercury. Has superconductivity. In the same year, Onnes was awarded the 1913 Nobel Prize in Physics for his research on the properties of matter at low temperatures and the liquefaction of helium.
And the concept of superconductivity followed.
Previously, superconductors had to work in extremely low-temperature environments. There are mainly four types of technical classification: low-temperature superconductivity, which requires a temperature of liquid nitrogen below 40K (about -233.15°C) to reach the superconducting state. Common low-temperature superconductors include niobium-titanium alloys, niobium-titanium alloys, and Aluminum alloys, etc.; metal superconductors, common metal superconductors include lead, aluminum, mercury, etc., which require very low temperatures to achieve superconductivity; iron-based superconductivity; cuprates superconductors, mainly copper oxides (cuprates) The advantage of superconducting materials with high composition is that the superconducting transition temperature is relatively high, and superconductivity can be realized above the temperature of liquid ammonia.
In 1987, researchers discovered a copper-containing superconductor that operates at minus 196 degrees Celsius. Follow-up experiments eventually raised the superconducting temperature to minus 140 degrees Celsius.
From an academic perspective, currently, no truly practical room-temperature superconductors and materials have been developed in the world, so many scientists have begun continuous experiments to seek the world’s first room-temperature superconductor to achieve a “revolutionary technological breakthrough”, mainly because superconductors are used for Magnets power particle accelerators and nuclear magnetic resonance equipment, which are the building blocks of quantum computers, which could eventually outperform the world’s best supercomputers. If they don’t require cryogenic temperatures and are easier to operate and manufacture, the industrial impact could be Wider.
Since 2023, there have been two main events that have catalyzed “room temperature superconductivity” and attracted widespread attention: the controversy over Diaz’s room temperature superconducting results in the United States and the experiments of the Korean scientific research team.
On March 7 this year, Ranga Dias, a physicist at the University of Rochester in New York, introduced new research progress at the annual meeting of the American Physical Society, saying that the superconductor created by the team can operate at room temperature and relatively low temperatures. Work under pressure.
This is not the first time Diaz has brought room-temperature superconductivity to the world. In 2020, Diaz published a paper stating that he had photochemically synthesized hydrogen, carbon and sulfur elements in a diamond pressure chamber to form a simple carbonaceous sulfide hydride (CSH) in the laboratory, and raised its superconducting critical temperature to 15℃. However, Nature believed that there was a problem with Diaz’s data processing method and that his experimental results could not be successfully reproduced, so the paper ended up being withdrawn.
This year, Diaz’s latest paper claimed that room temperature superconductivity can only be achieved at 10,000 times the atmospheric pressure, but in the end, no laboratory in the world realized the reproduction of this research, which was temporarily falsified.
On July 23, 4 months later, the team of the Quantum Energy Research Center of the Korea Institute of Science and Technology (KIST) published an article entitled “The First Room Temperature and Normal Pressure Superconductors” paper, describing the experimental discovery of a new room-temperature superconductor called LK-99. The paper is accompanied by a sister paper on arXiv, a paper in a Korean journal, a video demonstrating the achievement of a superconductor, and a patent application.
Among them, the author of the first article (arXiv: 2307. 12008) is Professor Young-Wan Kwon of Korea University, and the remaining two signed authors are Sukbae Lee and Ji-Hoon Kim. So far, this room temperature superconductivity paper has been published once Revised, the paper has 22 pages in total; the author of the second article (arXiv: 2307.12037) is Hyuntak Kim (from the College of William and Mary), and there are 6 signatures.
Titanium Media APP has learned that the content of the above two articles is roughly the same. Both claim to have discovered the first room temperature and normal pressure superconductor. The second article is more informative, providing detailed methods of material synthesis and demonstrating the magnetic levitation phenomenon. , and speculated in more detail on the mechanism leading to this room-temperature superconductivity phenomenon.
The paper shows that the Korean scientific research team used “modified lead apatite crystal structure (hereinafter referred to as LK-99, a copper-doped lead apatite)” in the material synthesis part. The synthesis method is direct, simple, cheap, and can even To achieve superconductivity at 127 degrees Celsius under normal pressure, the core of the research process is the following three steps.
Step 1: Use lead oxide and lead sulfate powders with a molar ratio of 1:1 to undergo a solid-phase chemical reaction at 725 degrees Celsius and 10-3 Torr (vacuum measurement) to synthesize yellow lead vitriol.
Step 2: Synthesize cuprous phosphide under the conditions of 550 degrees Celsius and 10-3 Torr (the first and second steps can be performed independently).
Step 3: After the products of the first and second steps are ground into powder, they are heated to 925 degrees Celsius under 10-3 Torr conditions to synthesize Cu-doped lead apatite (ie LK-99).
Similar to the feedback behind Diaz’s results, the experimental process of the Korean team is simple and direct, and the paper contains some wrong information, the data is not complete, and there is a lack of experience. In particular, the resistance measurement gives the IV curve current I at different temperatures. It is too small, the resistivity measurement accuracy is not enough, etc., so many industry experts have questioned this.
According to CCTV, Wen Haihu, director of the Superconducting Physics and Materials Research Center of Nanjing University, believes that what the Korean team demonstrated is not a superconducting phenomenon, but a “superconducting illusion.” The main reason is to achieve superconducting zero resistance and complete diamagnetism ( Meissner effect) two characteristics, the results of the paper do not fully meet the conditions.
What the Korean team demonstrated was not a superconducting phenomenon, but a “superconducting illusion.” The main reason was to achieve the two characteristics of zero resistance and complete diamagnetism (Meissner effect) of superconducting. The results of the paper did not fully meet the conditions.
The paper wants to explain the existence of superconductivity from three aspects: resistance measurement, magnetization measurement and magnetic levitation.
Among them, the “four-probe method” is usually used for resistance measurement. The main reason is that this method is contact-based and relatively stable. However, according to a Korean journal article they published last year, the electrode is measured with four sharp needle tips. This kind of measurement has There will be problems sometimes, because it is a needle tip, so there are problems with all aspects of contact, but it now displays the so-called resistance data, none of which is a very stable zero resistance in the noise state, and its data changes with the temperature. , so the data is still quite questionable.
The magnetization data does show diamagnetism, but the diamagnetism of other materials is measured using superconducting quantum interference device instruments. If the signal is large, it is generally correct, but when the signal is small, it will often give this illusion. Superconducting has its own hysteresis loop with a specific shape, which is not found in any other material, but this data information was not found in the article. Therefore, in magnetization measurement, although there is diamagnetism, it is difficult to say whether the diamagnetism itself is superconducting.
Finally, there is magnetic levitation. Magnetic levitation is a typical feature of the second type of superconductor. When a stable state is reached on a magnet, the superconductor and the magnet are stable, and it is not easy to press it in or remove it. It requires With force, the magnetic levitation it shows now is not like superconducting magnetic levitation, but a magnetic levitation state achieved after a balance between diamagnetism and gravity.
”So I feel that based on the above three points, there is currently no strong evidence that it is superconducting.” Wen Haihu said.
According to Susannah Speller, professor of materials science at Oxford, “it’s still early days and we don’t have strong evidence for superconductivity in these samples” because of the lack of clear hallmarks of superconductivity, such as magnetic field response and heat capacity. Other experts also expressed concern that the data could be explained by “errors in the experimental process and defects in the LK-99 sample.”
It is worth noting that the research work was led by two Korean scientists, Sukbae Lee and Jihoon Kim, both of whom graduated from the Chemistry Department of Korea University. The so-called LK-99, LK is actually the initials of the two scientists’ last names, and 99 is the time they believed they found this material (1999). They even established a quantum energy research center (Q-Center) to operate it. The superconductor preparation experiment.
However, the three authors of the first paper did not reach an agreement, resulting in “infighting”.
According to Yonhap News Agency’s report on July 28, Sukbae Lee stated over the phone that Professor Young-Wan Kwon published it on arXiv without the permission of other authors and insisted that he “requested that the paper be removed from the shelves.” He also revealed that research professor Kwon once served as the chief technology officer (CTO) of the Quantum Energy Research Institute, but he resigned as a director four months ago and currently has no relationship with the company. According to a person from Korea University, Professor Kwon has lost contact with the school.
Dr. Jihoon Kim stated that “these two papers have many flaws and were published without his permission”. It is reported that Sukbae Lee, Jihoon Kim and Young-Wan Kwon had previously hoped to apply for the paper to be published in Nature, but were rejected. However, the three people applied for a patent, and the patent was approved and made public in March 2023.
However, today, 8 days (192 hours) after the paper was released, things have reversed. Scientists from China, the United States and Russia successfully reproduced “room temperature superconductors” on the same day.
On August 1, the arXiv platform published at least four papers on superconductors, one of which was a paper by Sinéad Griffin, a nanostructured materials theory researcher at the Lawrence Berkeley National Laboratory (LBNL) in the United States. The team replicated the Korean team’s experiment and found that LK-99 crystal can achieve “room temperature superconductivity.”
The paper shows that the Griffin team used the U.S. Department of Energy’s supercomputer to conduct simulations and calculated through density functional theory (DFT) and GGA+U methods. They found that when copper replaced lead in apatite, it caused structural distortion. , resulting in an isolated flat band at the Fermi level (a common hallmark of known high-temperature superconductors), that is, the presence of a common feature of high transition temperatures in the superconductor family. All the calculated results are similar to the experimental results of the Korean LK-99 crystal, and the lattice parameters differ from the experimental results by 1%.
This experimental result provides a theoretical basis for the recent so-called “room temperature and normal pressure superconducting materials” by the Korean team, and provides new directions and inspirations for the research of superconducting materials.
It is reported that LBNL belongs to the National Laboratory of the U.S. Department of Energy. Since its establishment in 1931, it has trained 15 Nobel Prize winners. According to the Nature Index, the laboratory’s influence in the fields of physics and chemistry ranks first in the world.
The paper mentioned that it used a density functional theory calculation during the supercomputer simulation process and showed the calculated spin polarized electronic structure. The final theoretical results show that the LK-99 material of the South Korean team may indeed have the characteristics of “room temperature superconductivity” at the theoretical level. However, this requires copper to penetrate into specific locations in the molecule to achieve superconductivity, which means that the material is difficult to synthesize and prepare in reality.
Not only that, on Monday (July 31) Eastern Time, Taj Quantum, a company in Florida, also announced that it had developed a room-temperature superconductor and had obtained a patent. Its CEO Paul Lilly said that their superconducting material is a type II superconductor of graphene material that can work at normal pressure, but the company has not published any experimental data or papers to prove the effectiveness of their superconducting material. Performance and principle, and no other scientists have replicated or verified their experiments.
In Russia, Russian scientist Iris Alexandra successfully prepared LK-99 crystals with room-temperature diamagnetism, which is one of the hallmarks of superconducting crystals. The results were posted on Twitter.
In addition, on August 1, Chinese scientists also successfully reproduced the experiment of the Korean team.
Confirmed by Professor Chang Haixin of Huazhong University of Science and Technology, the UP owner of Station B “Guanshankou Man Technician” uploaded a video on the verification of LK99 on the 1st, showing a sample of tens of microns, using RuFeB magnets placed under the material, NS Polarity allows the material to exhibit diamagnetism.
According to the video, the research was conducted under the guidance of Professor Chang Haixin from the School of Materials at Huazhong University of Science and Technology, with postdoctoral fellow Wu Hao and doctoral student Yang Li verifying the synthesis of LK-99 crystals that can be magnetically levitated. The crystal’s levitation angle is larger than the magnetic levitation angle of the sample obtained by Sukbae Lee and others at the Korean Quantum Energy Research Center, and it is expected to achieve true contactless superconducting magnetic levitation.
As of press time, the video has been played more than 1.5 million times and has been liked by the official account of Station B of Huazhong University of Science and Technology. Chen Rui, chairman of Bilibili, also left a message in the comment area: “Bull (3 thumbs up)”.
However, in addition to the above-mentioned papers, according to public experimental data and videos published by netizens, the LK-99 synthesized in repeated experiments showed certain diamagnetic properties, but no superconducting phenomenon or superconducting magnetic levitation was observed.
Sun Yan from the Institute of Metal Research, Chinese Academy of Sciences said that they mainly conducted theoretical calculations. Judging from the calculation results, LK-99 has the possibility of room temperature superconductivity, “but it is not confirmed (not confirmed).” The research team of the School of Materials Science and Engineering of Beihang University tested the synthesized LK-99 and found that its room temperature resistance was not zero, and no magnetic levitation was observed.
In summary, the Korean team’s LK-99 room temperature superconductor experiment is theoretically feasible, but the synthesis is extremely difficult and the probability of recurrence is too low. The successful reproduction of magnetic levitation can only prove that LK-99 has certain diamagnetic properties, but cannot prove that it has the room-temperature superconducting characteristics claimed by the Korean team.