The world's first room-temperature, atmospheric-pressure superconductor! Booking a Nobel Prize
A group of Korean researchers (from the Korea Quantum Energy Research Center) have uploaded two papers to the preprint server ArXiv, reporting on a room-temperature superconductor: the critical temperature exceeds the boiling point of water, reaching up to 400 K (127 degrees Celsius).
The paper titled "The First Room-Temperature Ambient-Pressure Superconductor" by Sukbae Lee, Ji-Hoon Kim, and Young-Wan Kwon was first published on July 22 on arXiv. Sukbae Lee, JiHoon Kim, and Young-Wan Kwon published a paper titled "The First Room-Temperature Ambient-Pressure Superconductor" on arXiv.
Later on July 22, a paper co-authored by Sukbae Lee, Jihoon Kim, Hyun-Tak Kim, Sungyeon Im, SooMin An, and Keun Ho Auh was published in arXiv with the title "Superconductor Pb10-xCux()(PO4)6O showing levitra-induced superconductivity of Pb10-xCux()(PO4)6O". PO4)6O showing levitation at room temperature and atmospheric pressure and mechanism" was published on arXiv.
The paper claims that a modified lead apatite (called LK-99 in the paper, with the chemical formula Pb10-xCux(PO4)6O) is able to behave as a superconductor below 127°C under atmospheric pressure.
LK-99 is gray-black, the same color as typical superconductors. It has a three-dimensional network structure, a cylindrical column surrounded by the insulating tetrahedral structure PO4. The substitution of Cu2+ ions in LK-99 results in a volume reduction of 0.48%: because Cu2+ (87 pm) is smaller than Pb2+ ions (133 pm).
The stress occurs in the network part, which then leads to the emergence of superconductivity; at the same time, the EPR signal map of LK-99 confirms the presence of a quantum well (SQW) at the interface of Pb and phosphate - unlike previous studies, the superconductivity of LK-99 originates from a tiny structural deformation caused by a slight volume contraction of 0.48%.
In short, the reason why LK-99 exhibits superconductivity at room temperature and ambient pressure is that the unrelieved stress from the Cu2+ ion substitution of Pb2+ ions in LK-99 is at the same time appropriately transferred to the column-column interface. This proper deformation produces SQW in the interface without relaxation.
Phase diagram of Cu2+ doped Pb10-xCux(PO4)6O. IMT is the insulator-to-metal transition and MIT is the metal-to-insulator transition.IMT and MIT follow the same concepts and denote the interstitial-logarithmic interstitial transitions.IST is the insulator-superconductor transition (interstitial-interstitial transition) denoting the change of electrical in the same interstitial structure.IST is the insulator-superconductor transition (interstitial-gap transition) denoting the change of the electrical IST is an insulator-superconductor transition (gap-gap transition), indicating a change in electrical properties within the same gap structure.
The superconductivity of LK-99 can be demonstrated by critical temperature (Tc), zero resistivity, critical current (Ic), critical magnetic field (Hc) and Meissner effect. From the above experimental data, it can be judged that the critical temperature of LK-99 is above 400K.
At the end of the paper, the researchers said that all the evidence can prove that LK-99 is the world's first room temperature atmospheric pressure superconductor. "We believe that our new development will be a brand new historical event, opening a new era for mankind."
In recent days, the physics community has witnessed the release of this room-temperature superconductivity study; it has caused an uproar.
While the discovery sounds promising, the research must be approached with caution. Further rigorous and independent validation is needed before it can be widely accepted by the scientific community. The scientific community must replicate the experiments and results to confirm the reproducibility and reliability of the findings.
Peer review and scrutiny by experts in the field also help to validate the claims made in the study. In addition, researchers need to conduct extensive studies to understand the fundamental mechanisms behind LK-99 room temperature superconductivity.
In the paper, the authors give detailed steps for the synthesis.
(a) Layout of hermetically sealed vacuum transistors with mixed power. (b), (c), and (d) Heat treatment conditions for langite, Cu3P, and Pb10-xCux(PO4)O (0.9<x<1.1), respectively (e) Pre-mixed powder of all the components before the reaction, which is white to light gray. (f) Pictures of sealed samples after reaction, (g) process of removing samples from the furnace, (h) shape of samples in sealed quartz tubes, (i) shape of samples during each process.
In the first step, pyrrhotite was synthesized by chemical reaction. Lead oxide and lead sulfate powders were homogeneously mixed in a ceramic crucible at a ratio of 50% each. The powder mixture was heated in a furnace at 725 degrees Celsius for 24 hours in the presence of air. During the heating process, the mixture undergoes a chemical reaction to produce pyrite.
In the second step, copper phosphite crystals are synthesized. Copper and phosphorus powders are mixed proportionally in a crucible. The powder mixture is sealed in a thyristor of 20 cm per gram with a vacuum level of 10-3 times torr. The sealed tube containing the powder mixture is heated in a furnace at 550 degrees Celsius for 48 hours, during which time the mixture reacts and forms cuprous phosphide crystals.
In the third step, the pyrite and cuprous phosphide crystals were ground into powder and mixed in a crucible, and then sealed into a thyristor with a vacuum of 10-3 times the square torr. The sealed tube containing the mixed powder is heated in a furnace at 925 degrees Celsius for 5-20 hours. During this process, the mixture reacts and is converted into the final material. In this case, the sulfur element in the lead sulfate evaporates during the reaction.
Many researchers have said that these steps are not complicated and that many laboratories can try to reproduce them - if what the authors say is true, then the LK-99 material can be reproduced in 34 hours. It's precisely because of this simplicity that the study is so skeptical, and many feel it's too good to be true: is it really true that "good ingredients often require only the simplest of cooking methods"?
So far, several experimental teams have indicated that they are working on replicating the material, waiting for superconductivity to reappear.
While this has generated a lot of excitement, it has also raised a lot of questions. For example, Susannah Speller and Chris Grovenor of the University of Oxford say that when a material becomes a superconductor, it will exhibit distinct characteristics in many experiments; however, for two of those characteristics: response to magnetic fields and heat capacity, the data in the paper fails to make an effective demonstration.
At the same time, the theoretical models used by the paper in explaining why the new material can become superconducting under completely different conditions than before have been questioned by the researchers. For example, the paper only uses the results of a magnetic levitation experiment to prove the emergence of the "Meissner effect", and there is no data on the magnetization rate - one of the most important criteria for determining whether a material enters the superconducting state.
The paper has also been analyzed by a number of industry insiders on Zhihu. They were generally negative, and fudged quite a few of the images in the paper. In response to these questions, Hyun-Tak Kim also admitted some shortcomings of the experiment in an interview with New Scientist yesterday: he explained the appearance of the "Meissner effect" in the paper; according to his account, although there is a video proving the appearance of the "Meissner effect", there is only one video proving the appearance of the "Meissner effect". According to his account, although there is video evidence of the Meissner effect, only one of the planes is in levitation, so only part of it actually becomes a superconductor.
At the same time, he supports anyone who wants to reproduce his team's results.
It is well known that papers on the arXiv are not peer-reviewed in the industry, and there have been many previous oopses in this field. But as usual, just proving that room-temperature superconductivity can exist is a huge step forward.
In fact, replicating the experiments according to the paper should be soon enough that we can wait a little longer.
The phenomenon of superconductivity was first discovered in 1911 by a team of researchers at Leiden University in the Netherlands by H.K. Onnes - the resistance of metallic mercury suddenly disappeared to zero below 4.2 K, which Onnes named "superconductivity," meaning Superconductivity", meaning "super conductivity". Subsequently, more than a hundred years, all kinds of superconducting materials have been discovered, and there are now thousands of known superconducting materials, covering monolithic metals, alloys, intermetallic compounds, transition-metal sulfur/phosphorus compounds, and even organic compounds.
Superconducting materials are of immense value in almost all electrical and magnetic related applications due to their special physical properties such as absolute zero resistance and perfect antimagnetic properties.
In the last decade, high-pressure compression technology has dominated the search for high-temperature superconductivity. Leading the way was the "chemical pre-compression" of hydrogen-dominated alloys, which demonstrated the critical superconducting transition temperatures (Tc) of the rare-earth hydrides LaH10 and YH9 at megapascals close to the freezing point of water.
The age and critical temperature of discovery of various superconductors, with typical material structures shown in the inset. From: Science China
After 37 years of research, copper oxide and nickel oxide superconductors are the unconventional superconducting materials known to have superconducting transition temperatures that break through the temperature region of liquid nitrogen.
Unlike high-temperature superconductivity, room-temperature superconductivity is important because it has the potential to revolutionize multiple aspects of science and technology. One of the most significant advantages of room-temperature superconductors is their unprecedented energy efficiency. Conventional superconductors require extremely low temperatures to function, which makes them limited and energy-intensive for practical applications. However, with room-temperature superconductors, the resistance of the transmission and distribution system is virtually zero, resulting in minimal energy loss.
In addition, the advent of room-temperature superconductivity could pave the way for groundbreaking advances in transportation, such as high-speed trains that can travel without using large amounts of energy. In addition, superconducting materials could be used in energy storage devices, providing efficient and compact solutions for grid-level energy storage and portable electronics.
Quantum computing will be a direct beneficiary of this work, and with room-temperature superconductivity, quantum computing will become more practical and accessible. Most quantum computers need to operate at ultra-low temperatures close to absolute zero to minimize noise. This extreme cooling requirement is not only technically challenging and costly, but also limits the scalability of quantum computing systems. Room-temperature superconductors, with their ability to conduct electricity without resistance at ambient temperatures, can provide a stable, controlled environment for quantum bits without the need for complex cooling systems.
Scientific performance in this area has also been "full of oomph".
The earliest sensation was caused in 2017, Harvard University's R. P. Dias and I. F. Silvera announced the realization of metallic hydrogen at 495 GPa, they observed hydrogen in the process of increasing pressure, from transparent hydrogen molecules solid, to black opaque semiconducting hydrogen, and ultimately to the metal with metallic reflections of metallic hydrogen, the paper was published in the journal "Science".
Just when the industry was cheering and expecting Dias and Silvera to further measure whether metallic hydrogen has room temperature superconductivity, they accidentally broke the diamond during the experiment and did not repeat the experiment later. What followed was a chorus of skepticism that the high-pressure technique of nearly 500 GPa, which is difficult but still achievable by a few research groups internationally, had not been repeated out of the metallic hydrogen experiment.
On October 14, 2020, Nature published a paper titled "Room-temperature superconductivity in hydrocarbon sulfides," with first author E. Snider and corresponding author R. P. Dias - by this time Dias was an assistant professor at the University of Rochester. The key result of the paper was that the C-S-H ternary system could achieve superconductivity around 288 K at around 267 GPa, corresponding to a temperature of 15°C. The Tc of superconducting materials, for the first time, was broken above 0°C: just one step away from the room temperature of 300 K.
However, like Dias' paper on metallic hydrogen, this paper was widely questioned by the scientific community from the day it was published. Experimental physicists generally felt that "the data in the paper are too nice, the transition to zero resistance in superconductivity is very steep, and there are a series of problems with the associated results", while theoretical physicists felt that "the data results are contrary to fundamental physics".
Data results from the paper on zero resistance and antimagnetism
In response, Dias et al. posted a paper at arXiv in 2021 giving the raw data on magnetizability as well as a background deduction method.
The background deduction method for magnetization rate posted by Dias et al. and the analysis of questioning scholars
Even more scholars have analyzed the so-called raw data of Dias et al. in great detail, and firmly believe that there are obvious "artificial traces" in these data: the so-called "superconducting signal" comes from the superposition of a segmented function and a continuous function; the so-called "background signal" comes from the superposition of a segmented function and a continuous function; and the so-called "background signal" comes from the superposition of a segmented function and a continuous function. The so-called "background signal" is artificially constructed non-random noise, and the so-called "raw data" is the result of the addition of the two! They used the word "pathological" to describe the results of the magnetization data in Dias' paper. It was this paper that led to the September 26, 2022 retraction decision by the editors of Nature.
On March 8 of this year, at the March meeting of the American Physical Society (APS), Ranga Dias formally presented the discovery of superconductivity in ternary hydrides (N-Lu-H) at room-temperature conditions (1 GPa/1000 MPa, 20°C). At this conference, experimental teams reported on the recent development of new materials that exhibit superconductivity under near-ambient conditions: these compounds were synthesized under high-pressure-high-temperature conditions and suggest that the dawn of ambient superconductivity and applied technologies has arrived.
Unfortunately, many teams at home and abroad then immediately tried to reproduce the experiments, but they all failed, and skepticism was widespread. Institute of Physics of the Chinese Academy of Sciences, Nanjing University team have published a paper "fake", said did not reproduce the success: binary lutetium hydroxide (Lu4H23), in 71K (-202 ° C), 218 GPa conditions to achieve superconducting transition, this result is neither room temperature, nor near normal pressure.
In June of this year, another paper was published by a member of the US National Academy of Sciences stating that the results have been reproduced preliminarily; and noting that other teams have not succeeded because of improper sample preparation.
Nowadays, the room temperature superconductor revolution is in the limelight, and this time, once it is proved true, there is no doubt that it will be a Nobel Prize-level breakthrough of the century. I believe that in a few days, we will see whether the room-temperature superconductor can be reproduced or not.
Reference link:
[1]https://arxiv.org/abs/2307.12008
[2]https://arxiv.org/abs/2307.12037
[3]https://mp.weixin.qq.com/s/8OUDNjZU_oECYv65OKn7XA
[4]https://mp.weixin.qq.com/s/tXhcULZan2bMGJ2uUHqNCw
[5]https://mp.weixin.qq.com/s/kQNs5WaU39e-bIlri6Wj4Q
[6]https://thequantuminsider.com/2023/07/26/researchers-claim-they-developed-a-room-temperature-superconductor/
