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A comprehensive guide to room temperature superconductivity: everything you need to know about Superconductivity and superconducting materials

What is superconductivity?

Superconductivity is the phenomenon whereby a material‘s resistance becomes zero at a temperature below which it is called the critical temperature.
Superconductivity is the phenomenon in which a material’s electrical resistance becomes zero at a temperature below which it is called the critical temperature. Superconductivity means that current can pass through materials with zero resistance. But strictly speaking, the resistance is zero at a certain temperature. Superconducting not only has the characteristic of zero resistance but also can have complete Diamagnetism – which makes superconductors almost have no energy consumption in the process of transmitting current, and superconducting materials with a cross-sectional area of every square centimeter can carry more current; However, conventional materials typically consume a large amount of energy during the conductive process. In the early days of superconductivity, the critical temperature was low, and the ability to obtain low temperatures was very demanding. In 1908, the Dutch physicist Onnes succeeded in liquefying helium, and human beings have since been able to obtain low temperatures as low as -269°C (4.2 K) through the phase transition of helium. Subsequently, in 1911, Onnes discovered the earliest superconducting material when he used liquid helium to lower the temperature of mercury to 4.15K and found that the resistance of mercury dropped to zero.

Superconductivity is the phenomenon whereby a material’s resistance becomes zero below a certain temperature

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Figure.1 Superconductivity is the phenomenon whereby a material’s resistance becomes zero below a certain temperature

What is room temperature superconductivity?

Room temperature superconductivity that is, the Superconductivity realized at room temperature. Superconductivity was initially observed at very low temperatures close to Absolute zero, and most superconductors only work at temperatures close to Absolute zero. If humans achieve room temperature superconductivity under normal physical conditions, it is expected to improve the efficiency of electrical conductors and devices by minimizing heat generation, and enable large-scale applications of superconducting materials in production and life, comprehensively and profoundly changing human society.
Conventional superconducting materials need to be cooled to very low temperatures to achieve zero resistance, which makes superconducting technology limited in its application and costly. However, room-temperature superconductivity has always been the goal of researchers. Currently, the research of room temperature superconductivity is mainly focused on carbon, sulfur, phosphorus, and other non-metallic element compounds. The special electronic structure in these compounds makes them superconducting in nature.

What is superconducting material?

Superconducting materials exhibit properties such as zero resistance and repulsive magnetic field lines under certain low-temperature conditions. Generally speaking, materials can be classified into insulators, semiconductors, and conductors based on their room temperature resistivity, from high to low. Most metals are good conductors, and their resistivity at room temperature is very small but not zero, around 10-12m Ω∙cm.
When a material is dropped below a certain temperature, the resistance suddenly drops to zero, and all external magnetic field lines of force are discharged from the material, resulting in zero Magnetic flux density in the body; that is, a zero resistance state and complete Diamagnetism occur simultaneously. In this state, the material enters a superconducting state called a superconducting material.
The series of magical properties of superconductors means that we can stably utilize them at low temperatures, such as achieving lossless power transmission, stable, strong magnetic fields, and high-speed maglev vehicles. Because of this, since the discovery of superconductivity, people’s exploration of superconducting materials has been constantly advancing, and their enthusiasm for studying the microscopic mechanisms and applications of superconductivity has never diminished.

Classification of superconducting materials

Superconducting materials are divided into low-temperature superconducting materials and High-temperature superconductivity materials.
1. Low temperature superconducting materials
Low-temperature superconducting materials are superconducting materials with a low critical transition temperature (Tc<30K=operating at liquid helium temperature) divided into metals, alloys, and compounds. The low-temperature superconducting metal with practical value is Nb (niobium), with a Tc of 9.3K, made into thin film materials for weak current applications. Alloy-based low-temperature superconducting materials are composed of binary or ternary alloys based on Nb β Phase solid solution, Tc is above 9K.
Low-temperature superconducting materials generally need to work in expensive liquid helium environments. Due to the expensive and inconvenient methods of liquid helium refrigeration, the application of low-temperature superconductors has not been developed on a large scale for a long time. The application of low-temperature superconducting materials can be divided into strong electrical applications, mainly including superconductivity in strong magnetic fields and high current transport; Weak current applications mainly include the application of superconductivity in Microelectronics and precision measurement.
2. High-temperature superconductivity materials
High-temperature superconductor (HTS) materials have two important characteristics: superconductivity and Diamagnetism. To achieve practical applications of superconductors, it is first necessary to have easily found superconducting materials. The main research direction is to search for superconductor materials that can exist at higher temperatures.
High-temperature superconductivity materials are widely used and can be roughly divided into three categories: high-current applications, electronics applications, and Diamagnetism applications. High current applications are due to superconductors having zero resistance and complete Diamagnetism so that they can obtain stable and strong magnetic fields with little power consumption. One of the basic characteristics of superconductors is their ideal conductivity when in a superconducting state, and due to their much stronger current carrying capacity than conventional conductors, they can transmit large currents and generate strong magnetic fields without resistance heat loss.
The basic characteristics of electrical equipment are high current, strong magnetic field, and high voltage. Therefore, using superconducting materials in electrical equipment can reduce electrical losses, improve efficiency, reduce volume, reduce weight, reduce costs, and increase the device’s ultimate capacity. The application of superconducting materials has brought a qualitative leap to electrical technology, and much electrical equipment that could not have been achieved in the past has become a reality or is about to become a reality due to the use of superconducting technology.
The uneven distribution of power resources and loads in China makes long-distance and low-loss transmission technology very urgent. Superconducting materials, due to their zero resistance characteristics and much higher current carrying capacity than conventional conductors, can transport extremely high currents and power without electrical power loss. According to statistics, the current situation, if copper or aluminum conductors are converted into superconductors, saving electricity in China alone is equivalent to building dozens of large power plants. The applications of superconducting materials in these areas are the most attractive.

Performance characteristics of superconducting materials

1. Complete conductivity
Experimental studies have shown that when the temperature drops to a certain critical temperature, the characteristic of superconductors with a sudden change in resistance to zero is called complete conductivity, also known as the zero resistance effect.
2. Complete Diamagnetism
In 1933, Meisner and Orsenfeld measured the magnetic field distribution of single crystal tin balls. They found that whether it was cooling before applying a magnetic field or cooling after applying a magnetic field, as long as the temperature of the tin ball reached the superconducting critical temperature Tc, the magnetic field lines seemed to be completely excluded from the superconductor. As long as T<Tc, the total Magnetic flux density in the superconductor is zero; that is, the superconductor has complete Diamagnetism.
3. Josephson effect
Microparticles such as electrons have Wave–particle duality. When two metals are separated by an insulating medium with a thickness of tens to hundreds of A, electrons can move through the barrier. After applying voltage, a tunnel current can be formed, which is called the tunnel effect. After replacing the two metals in the above device with superconductors, when the thickness of the dielectric layer is reduced to about 30A, the long-range coherence effect caused by the superconducting electron pair will also generate a tunneling effect, known as the Josephson effect.
4. Criticality
Superconducting materials have critical temperatures, magnetic fields, and current densities. Only those below their critical values can demonstrate their superconductivity. Once exceeded, they will lose their superconductivity. In addition, there is Coherence length. Guidance can only maintain its superconductivity at a certain scale.

How to obtain higher critical temperature superconductors?

High pressure is a very effective way. Under high pressure, raw materials are in close contact with each other, and the rate of a chemical reaction is much faster than at atmospheric pressure, which improves the efficiency of material synthesis and holds the promise of preparing new materials that are unstable at atmospheric pressure. Applying high pressure to a material can change the spacing of atoms within the material, and the structural phase transition can be induced, thus obtaining special electronic structures and physical states that are difficult to obtain under normal pressure. For some superconducting materials, high pressure often helps to increase their Tc. For example, in Ca monomers at 216 GPa Tc=29K, the critical temperature of the Hg-1223 system is further increased to 164K under high pressure. Theoretically, it is predicted that the metallic hydrogen under high pressure is a superconductor, and the critical temperature can be close to the room temperature (generally defaulted to T=300K). However, because of the huge challenges in material synthesis and experimental measurements under high pressure, especially the ultrahigh-pressure technology realized by using a diamond top-anvil is very difficult, the high-pressure superconductivity of metallic hydrogen has yet to be realized. 2016, Dalladay – Simpson et al. at the University of Edinburgh in the United Kingdom, a “new solid state” of hydrogen was obtained at 325 GPa, suggesting it may be a “new solid state” of hydrogen. “In 2017, Dias and Silvera’s group at Harvard University announced the realization of metallic hydrogen at 495 GPa. However, the results were not replicated when they broke a diamond while measuring room-temperature superconductivity due to an operational error. In December 2014, scientists at the Max Planck Institute for Chemistry in Germany Drozdov et al. announced the discovery of 190 K superconductivity in the H-S system at 150 GPa, breaking the 164 K record held by Hg-1223 for many years. In August 2018, they announced again that the LaHx system had a Tc of 215 K at 150 GPa, and the U.S.-based team of Somayazulu followed by announcing that the superconductivity of LaH10 could reach a Tc of 260 K ( 190 GPa environment).
Record of discovery dates and critical temperatures of various superconducting materials, with a typical superconductor structure in the inset.

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Figure.2 (Color online) Record of discovery dates and critical temperatures of various superconducting materials, with a typical superconductor structure in the inset
Recently, the Dias group at the University of Rochester (USA) published the results of high-voltage superconductivity in the C-S-H system in Nature. They loaded micron-sized C and S particles and hydrogen into a diamond counter anvil, pressurized it to 4 GPa, and heated it with a laser beam to react fully. Pressurization continued above 37 GPa, and Raman spectroscopy showed that new phases were created. Superconductivity was observed at 147 K at 138 GPa and increased to 194 K at 220 GPa, similar to the H-S system. Continuing to increase the pressure to around 270 GPa, superconductivity of up to 287.7 K was finally obtained. Resistance measurements show that the system has a very narrow superconducting transition width. An antimagnetic signal is detected at least up to 190 GPa, where the magnetic field suppresses the superconducting transition temperature. The critical field at zero temperature is fitted to be about 62 T. This result exceeds the previous record of a critical temperature of 260 K in the LaH10 system, which is much closer to the room temperature, as shown in the paper titled “Room-temperature superconductivity in the C-S-H system”. The results surpass the previous record of 260 K in LaH10, which is closer to room temperature and are summarized in a paper entitled “Room temperature superconductivity in the C-S-H system” (Fig. 2). Previously, the superconductivity of the H-S and La-H systems was considered to be consistent with the BCS theoretical picture of strong electric-phonon coupling. Its Tc was usually inferred from MacMillan’s formula. Although the structure of the C-S-H system has not yet been confirmed, its high-pressure room-temperature superconductivity is likely to belong to a similar situation.
However, structural and physical measurements of materials at high pressure are extremely difficult, and several groups need to reproduce the high-pressure superconductivity of hydride-containing materials before they can be finally confirmed. The steep transition widths of the resistance data reported for the C-S-H system, both at zero and strong magnetic fields, do not exclude other superconductivity-like phenomena, especially since some of the physical parameters derived from them do not seem to be fully consistent with the superconducting characteristics. The physical parameters derived are not consistent with the superconductivity characteristics. In addition, the high critical temperature superconducting materials at high pressure are hardly of practical value, and we need to be cautiously optimistic about the high-pressure room-temperature superconductivity. In recent years, high-pressure studies of hydrogen-rich compounds from binary to polymerized compounds have broken through the confined thinking of monomolecular metallic hydrogen, implying that superconducting materials with higher Tc may be discovered. Suppose we can find a superconductor from hydrogen-rich compounds in the future which can maintain superconductivity and stability at room temperature under low or even atmospheric pressure. In that case, it will be a breakthrough in the research of superconductivity mechanisms and applications.

Applications of superconductivity

Superconductivity has a broad range of applications, categorized into three aspects: high current, large magnetic field, and small magnetic field.

  1. In terms of high current, the resistance of the material itself is zero in the superconducting state, which can be used to conduct large currents, and the downstream application scenarios include current limiters, current leads, transmission cables, communication cables, and so on;
  2. In terms of the large magnetic field, according to the theory of electromagnetism, the use of alternating current can generate a magnetic field, so the superconducting phenomenon can be used to obtain a large magnetic field through the large current, downstream application scenarios include large scientific instruments, large medical instruments, advanced transportation, controlled nuclear fusion devices, and so on;
  3. In terms of the small magnetic field, due to the superconducting quantum interference effect of superconductors, this can be made a superconducting quantum interference device (Superconducting Quantum Interference Device, SQUID), which is a more sensitive sensor for detecting magnetic signals. It can distinguish a 10-15T magnetic field; its downstream application scenario is an advanced magnetic field detector.

Where electricity is used, superconductors are of great significance, and when superconductors realize room-temperature superconductivity, their applications are noted to infiltrate all aspects of life.

  • 1. Superconducting electrical appliances: superconductors have no resistance and will greatly promote using existing electronic technology. Our daily applications of electronic technology are based on electrical circuits with resistance; due to the resistance generated by the consumption of electricity is huge, people, to resistance generated by the heat dissipation problem, invested countless resources. Computers will become superconducting computers; imagine your computer without resistors, no more heat dissipation and computers can be thinner and lighter. With integrated circuits using superconducting transistors, computers can have tens and hundreds of times speed increase directly; Electricity use is more efficient, the power consumption at home is directly reduced, but the light bulb is brighter, the electric car runs faster, electrical appliances have become more convenient, and more fine electrical components can be used in our lives. It is said that many companies are already working on superconducting and quantum computers.
  • 2. Quantum computer: now has been developed, two quantum computers; one is based on electromagnetic laser technology, and one is based on superconducting microwave technology. IBM’s quantum computer based on superconducting microwave technology has allowed people to see the feasibility of superconductors in the field of computers.
  • 3. Superconducting power generation: There are currently two meanings of superconducting generators. One meaning is to replace the ordinary generator’s copper windings with superconductor windings to increase current density and magnetic field strength, with large generating capacity, small size, lightweight, low reactance, and high-efficiency advantages. Another meaning refers to the superconducting magnetic fluid generator. The magnetic fluid generator has the advantages of high efficiency and large power generation capacity. Still, the traditional magnet produces a large loss during power generation, while the superconducting magnet has a small loss, which can compensate for this shortcoming. Power generation losses are minimized, which may also make power generation easier; much energy around us can be used as power generation components to provide daily electricity, such as solar and sports energy.
  • 4. Superconducting power transmission: superconducting wires and superconducting transformers made of superconducting materials can deliver electricity to users almost without loss. According to statistics, with copper or aluminum wire transmission, about 15% of the power loss in the transmission line, just in China, the annual power loss of more than 100 billion degrees. If changed to superconducting power transmission, the power saved is equivalent to dozens of new large power plants.
  • 5. Magnetic levitation transportation: superconducting magnetic levitation train: the use of superconducting material anti-magnetism, superconducting material will be placed on the top of a piece of permanent magnet due to the magnet’s magnetic lines of force cannot pass through the superconductor, the magnet and the superconductor between the repulsive force will be generated, so that the superconductor levitation in the top of the magnet. This magnetic levitation effect can be utilized to create high-speed superconducting maglev trains. Maglev cars: These cars are said to have already been invented but could enter the practical stage if superconductor technology matures. Maglev tires, a prototype of which has been reportedly invented by a Chinese boy, have high-performance characteristics not found in current tires. There are also maglev skateboards, which may replace our daily walking.
  • 6. Magnetic levitation machinery: the magnetic levitation characteristics applied to the research and development of machinery can make the important components without friction, mechanical braking efficiency and speed will be greatly increased, and can do many functions that the existing machinery cannot do.
  • 7. Magnetic levitation construction: magnetic levitation technology can make human beings utilize space more efficiently; perhaps in the future, living in the air is no longer a dream. Our life will become incredibly convenient when household goods use magnetic levitation technology.
  • 8. Superconducting medical treatment: It is said that the medical industry now has a superconducting magnetic resonance instrument, which can diagnose many important diseases.
  • 9. Nuclear fusion reactor “magnetic closure”: nuclear fusion reaction, the internal temperature of up to 100-200 million degrees Celsius; no conventional material can accommodate these substances. The strong magnetic field generated by superconductors can be used as a “magnetic closure” to enclose and constrain the ultra-high-temperature plasma in a thermonuclear reactor and then slowly release it, thus making controlled fusion energy a promising new energy source in the 21st century. Due to the wide range of fusion raw materials, the energy problem is expected to be completely solved. Even long-distance space travel will become possible.
  • 10. Superconducting gravity simulation: there is no gravity in the spacecraft, which leads to the movement of astronauts in the spacecraft being greatly restricted if you can also walk on the spacecraft as if it were flat, it is very important to the astronauts’ operations and even to the life on the spacecraft. It may be possible to simulate this gravity effect through the force of room-temperature superconductors.

The phenomenon of superconductivity is closely related to human productive life. Superconducting devices used commercially include magnetic levitation trains, nuclear magnetic resonance spectrometers, nuclear magnetic resonance imaging systems, and high-energy synchrotron radiation light sources.
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Figure.3 China’s High-Speed Maglev Transportation System Leads the World
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Figure.4 Fully digitalized superconducting nuclear magnetic resonance spectrometer
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Figure.5 Medical superconducting magnetic resonance imaging system
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Figure.6 High-energy synchrotron radiation light source of national major scientific and technological infrastructure superconducting cavity
Still, the commercialization process of superconducting devices, such as controlled fusion tokamak devices, is also an important area of superconductivity applications. The Institute of Plasma Physics of the Chinese Academy of Sciences led the design and development of the EAST tokamak device, EAST by the experimental “Experimental”, “Advanced”, “Superconducting”, “Superconducting”, “Superconducting”, “Superconducting”, “Superconducting”, “Superconducting”. Advanced”, “Superconducting”, “Superconducting”, tokamak “Tokamak” are four words spelled with the initials; their Chinese meaning is “advanced experimental superconducting tokamak”, the same time, and “EAST is the first fully superconducting tokamak designed and developed by China.
Although superconducting materials have a wide range of uses, previous superconducting materials relied on low temperatures, most of which required liquid helium and liquid nitrogen refrigeration to maintain superconductivity, which was costly. Room-temperature superconducting materials do not rely on refrigeration to maintain the superconducting state. If a breakthrough is made, the cost of superconducting technology for human beings is expected to reduce significantly.

Korea’s room-temperature superconductivity situation

It’s material system this time, first of all, the United States Diaz in March Physical Society reported the superconductor LK-99 looks a little more reliable because the United States Diaz’s report is nearly normal pressure, but also 10,000 atmospheres under 294K superconductor, equivalent to superconducting transition temperature is 21 degrees; South Koreans this time the report is no pressure, superconducting transition temperature up to 400K, equivalent to 127 The South Korean superconductor report this time is that no pressure is needed. The superconducting transition temperature is 400K, equivalent to 127 degrees. If it is a real superconductor, this Korean superconductor is extremely significant because there is a 107 degree temperature difference between 127 degrees and 20 degrees room temperature, which is much space.
There has yet to be proof that this is a true superconductor, and from the report, it looks like many of the measurements need to be fixed, but it can’t be proven wrong.
Looking at the material system, there should be some superconductivity or at least some antimagnetism, but whether the antimagnetism is due to superconductivity has yet to be proven repeatedly. From the reported results, it is flawed, but there may be superconductivity.
It is a signal to the whole field of superconductivity, inspiring superconductivity through material systems.
It has material systems such as oxygen, phosphorus, lead, copper, etc., all readily available and inexpensive. If zinc or lead-zinc is used for substitution, it has the potential to show complete superconductivity. It is still very significant to study new material systems.
First, the experimental systems need to be verified by other laboratories. Second, the experimental data are real or fake. Third, measurement errors may lead to misrecognized experimental phenomena.
Nature rejected the Korean report. This time, the experimental system in Korea is relatively easy to reproduce, which is phosphate plus oxygen, while the previous one in the U.S. Diaz is not easy to reproduce. This time there may be a laboratory replication within a week or two, and the proof can be obtained soon.

What is the superconducting material LK-99?

On March 2, 2023, South Korean patent WO2023027536A1 was issued, in which South Korean scholars Lee and Kim et al. disclosed a superconducting material called LK-99, which can achieve superconductivity at room temperature and atmospheric pressure. The LK-99 material was named after Lee and Kim’s initials spliced together and suffixed with 1999, the original discovery.
On July 22, 2023, South Korean scholar Young-Wan Kwon and American scholar Hyun-Tak Kim, under the names of Lee and Kim, respectively, made public their research papers on the Arxiv website, which included the production process, molecular structure, and performance index measurements of the LK-99 material, and caused a sensation by pointing out that the LK-99 was indeed a room-temperature superconducting material. However, shortly after that, on July 28, 2023, Lee and Kim, among others, said in an interview with Yonhap News Agency that the contents of the two papers above were incomplete and had many flaws and that they would remove the papers from their website and compile the research results, send them to official academic journals, and validate the results through peer evaluation.
LK-99 caused a sensation after its release, and scholars from various countries started experimental validation one after another, and some of the validation results were relatively optimistic.
On August 1, 2023, Griffin, a scholar at the University of California, Berkeley, made public his research results, stating that the properties of the LK-99 material had been verified using density functional theory (DFT), and the results showed that some of the atoms in the material had many of the key properties of a superconductor.
On August 1, 2023, the Securities Times reported the validation progress of Chinese scholars: “Hao Wu, a postdoctoral fellow, and Yang Li, a doctoral student at the School of Materials of Huazhong University of Science and Technology (HUST), under the guidance of Prof. Chang Haixin, have succeeded in synthesizing for the first time validated LK-99 crystals that can be magnetically levitated, and which are levitated at a greater angle of magnetic levitation than that of the samples obtained by Sukbae Lee et al., the It is expected to realize
truly contactless superconducting magnetic levitation.”
Table.1 Recent breakthroughs in the field of superconducting materials

Time Country Type Specific progress
2023/3/2 Korea experimental study  Discovered LK-99 material that can achieve superconductivity at room temperature and atmospheric pressure
2023/7/22 Korea experimental study  Published the production process and performance indicators of LK-99 material
2023/7/22 United States experimental study  Published the production process and performance indicators of LK-99 material
2023/8/1 United States Theoretical calculations The LK-99 material system has the potential to achieve room temperature superconductivity
2023/8/1 China experimental study Reproduced the LK-99 material and observed the magnetic levitation characteristics of superconductors

Superconductivity is a phenomenon that has multiple uses and relevance to human production and life
Superconductivity is the phenomenon in which the resistance of a material drops to zero below a certain temperature. Large currents and magnetic fields can be obtained by utilizing this phenomenon, and special superconducting sensors can be produced to detect small magnetic fields precisely. Based on the phenomenon of superconductivity, humanity has designed a variety of advanced vehicles and large-scale scientific machines, which are now in commercial use. However, all superconductors currently in commercial use rely on low temperatures and require constant cooling to maintain the superconducting state during use, greatly increasing the cost of superconducting devices. If a breakthrough is made in room temperature superconductivity, the cost of existing advanced transportation and scientific instruments will be significantly reduced.
Phosphorus, lead, and copper are key raw materials for LK-99 production
Lee and Kim et al. disclosed the chemical composition and production process of LK-99 material in their paper. The chemical formula of LK-99 material is Pb10-xCux(PO4)6O (0.9<x<1.1), and the production process is divided into 3 steps, which are the preparation of the lead precursor, the preparation of the copper-phosphorus precursor, and the production of the final product. According to the production process of LK-99 material published by Lee and Kim et al., lead sulfate, lead oxide, copper powder, and phosphorus powder are the key raw materials for the production of LK-99. According to the chemical formula of LK-99 material, it can be calculated that 0.074 tons of phosphorus, 0.742 tons of lead, and 0.025 tons of copper are needed to produce each ton of LK-99 material.
Yellow phosphorus: the main product of industrial production of phosphorus monomers
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There are two forms of phosphorus monomers commonly used in industry, yellow phosphorus, and red phosphorus, of which yellow phosphorus is the main product of the industrial production of phosphorus monomers. Yellow phosphorus is also known as white phosphorus; the pure product is a white waxy and glossy solid; under light and heat, it quickly changes into yellow color, the white phosphorus seen is a yellow product, so it is called yellow phosphorus. Yellow phosphorus is chemically active, easily spontaneous combustion, and needs to be stored in water. To make the phosphorus monomers safer and more stable, yellow phosphorus is often converted into red phosphorus, which is more stable, with higher melting and ignition points. It does not easy to react with oxygen at room temperature. Yellow phosphorus is transformed into red phosphorus when liquid yellow phosphorus is heated to 250-260℃ in a closed container. Due to the inconvenient transportation of yellow phosphorus, the import and export volume and domestic self-sufficiency are very small. The annual output 2022 is about 840,000 tons, and the total production capacity is about 1.45 million tons/year.
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Due to the inconvenient transportation of yellow phosphorus, the import and export volume and domestic self-sufficiency are very small. 2022 annual output is about 840,000 tons, and the total production capacity is about 1.45 million tons/year. As the production of yellow phosphorus requires a large amount of electricity, most domestic yellow phosphorus enterprises are located in the southwest region, using locally abundant and cheap hydropower resources to produce yellow phosphorus. But at the same time, due to hydropower’s instability, domestic yellow phosphorus’s capacity utilization rate is also limited, and the annual capacity utilization rate is stable near 60%.

LK-99 main raw material unit consumption disassembly

The chemical composition and production process of LK-99 material is disclosed in the paper of Lee and Kim et al. The chemical formula of LK-99 material is Pb10-xCux(PO4)6O (0.9<x<1.1), which shows that its main constituent elements are lead, phosphorus, copper, and oxygen. The production process is divided into 3 steps: the preparation of lead precursor, the preparation of copper-phosphorus precursor, and the production of the final product. The production process shows that the key raw materials of LK-99 material are lead sulfate, lead oxide, copper powder, and phosphorus powder.
Table.2 Production process of LK-99 material

Step Objective Raw material Specific operation
Step 1 Preparation of lead precursors Lead(II) sulfate and lead oxide mix Lead(II) sulfate and lead oxide in equal proportion and heat them for 24 hours at 725℃
Step 2 Preparation of copper phosphorus precursors Copper powder, phosphate powder Mix copper powder and phosphorus powder in a 3:1 ratio, place in a vacuum tube, and heat at 550℃ for 48 hours
Step 3 Preparation of finished materials Precursors mentioned earlier Grind the two precursors into powder and mix them, place them in a vacuum tube, and heat them at 925℃ for 5-20 hours

Source: Sukbae Lee, 《Superconductor Pb10-xCux(PO4)6O showing levitation at room temperature and atmospheric pressure and mechanism》.
Note: Lee and Kim et al. claim that the study needs to be completed and will be removed from the website, reorganized, and submitted to an official academic journal. The production process may change in future official publications.
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Figure.7 LK-99 material production process
The theoretical unit consumption of various raw materials can be calculated according to the chemical formula of LK-99 material. The chemical formula of LK-99 material is Pb10-xCux(PO4)6O(0.9<x<1.1), taking the x value as the intermediate value of 1, it can be obtained as Pb9Cu(PO4)6O, according to which the theoretical unit consumption of raw materials can be estimated. The calculation can be obtained, the production of each ton of LK-99 material, the theoretical need to consume 0.742 tons of lead, copper 0.025 tons, and phosphorus 0.074 tons.
Table.3 Estimated theoretical unit consumption of raw materials for producing LK-99 materials

Pb9Cu(PO4)6O Pb Cu P
Molecular weight 2514.3 207.2 63.5 31
Stoichiometry 1 9 1 6
Theoretical unit consumption formula 1 (207.2*9)/2514.3 (63.5*1)/2514.3 (31.0*6)/2514.3
Theoretical unit consumption (t/t) 1 0.742 0.025 0.074


Q: If the Korean one is true, is the temperature difference of a hundred degrees from room temperature something that must be improved to make it work better?
No. The equipment we make with superconducting materials must work at 20 degrees and 127 degrees difference of 107 degrees; the device in the process of working, even if it meets high temperature, is raised to more than 40 degrees but also has been kept below 127 degrees, can be used normally, so it is very rich, and compared with the previous superconductors have a greater advantage. So, it’s very significant, and if it’s true, then it has the potential to overturn the current material system.
Q: Some schools in China are doing reproducible experiments on this, so is it possible to realize it in the initial view?
It’s hard to understand high-temperature superconductors, but they probably exist. One is to look for something new, and one is to discover its applications. Superconductor resistance is zero, any superconductor has an intrinsic critical superconducting current, and of the thousands of superconductors discovered now, not many have a critical current that can meet practical applications; only five or six materials do. So, discovering new superconductors is of great physical significance, but the probability of practical application is very small.
Q: Is copper-oxygen the main superconducting material in China that can be used in practical applications?
Now the domestic one is niobium tris tin made by Western Superconductor, which has been applied in MRI, some low-temperature scientific projects such as collider, ion gas pedal, fusion demonstration device, etc., working in the temperature zone of 4.2K; the other is 77K yttrium-barium-copper-oxygen, which is dominated by three domestic companies, namely, Eastern Superconductor, Shanghai Superconductor, Shangchuang Superconductor, and the commercial application is mainly to do some small scientific devices, and induction heating, aiming at nuclear fusion. The commercial application is mainly to do some small scientific devices. Induction heating, aiming at nuclear fusion, the domestic also set up three nuclear fusion companies, and the future direction of development is based on yttrium-barium-copper-oxygen strips.
Q: Is yttrium-barium-copper-oxygen better in terms of commercialization?
In terms of intrinsic parameters, it is the best. One is the strongest current-carrying capacity, and the other is that it has the strongest magnetic field.
Q: Is there still a big market for these material systems in conventional applications like power transmission?
Shanghai did 1.2 kilometers of superconducting cables, and Shenzhen Ping An building below the superconducting cable also did 400 meters, are used yttrium barium copper oxygen. Shanghai pushes about five kilometers of cable based on yttrium barium copper oxygen. Nowadays, the demand for superconducting cables, induction heating, and nuclear fusion strips is still relatively large.
Q: Are there any barriers to the application of these materials?
One is the stability of the strips, and the other is the cost of the strips, which restricts the real large-scale application. The cost of the strip is still relatively large; generally speaking, a meter is about one hundred dollars, low can be about 60 dollars, and the performance is slightly worse.
Q: Why is the cost so high?
Yttrium barium copper-oxygen material is not expensive, actually very cheap. One is a problem regarding yield; the other overall capacity could be bigger; the relevant supporting industries are also more expensive, such as baseband are bought from abroad; a kilogram is also one or two thousand dollars. Similarly, the cost of polishing and plating is also relatively high.
Induction heating and nuclear fusion on the strip demand is still relatively large.
Q: Are there any obstacles or difficulties in applying these materials?
One is the stability of the strips, and the other is the cost of the strips, which restricts the real large-scale application. The cost of the strip is still relatively large; generally speaking, a meter is about one hundred dollars, low can be about 60 dollars, and performance is slightly worse.
Q: Why is the cost so high?
Yttrium barium copper-oxygen material is not expensive, actually very cheap. One is a problem regarding yield; the other overall capacity could be bigger; the relevant supporting industries are also more expensive, such as baseband are bought from abroad; a kilogram is also one or two thousand dollars. Similarly, the cost of polishing and plating are also relatively high.
At the same time, the demand has yet to come up; the capacity scale is too small, Shanghai’s superconductivity capacity of less than a thousand kilometers a year, and the eastern superconductivity of about 300 kilometers. Nuclear fusion a coil to be four or five hundred kilometers, the current production capacity is completely unable to meet. It cannot meet the need to expand production; now, several companies in Shanghai seem to be expanding production.
Like heating, motors, and magnetic levitation, these areas, with the stripping process to improve the stability of the further improvement of the overall performance, when used more solid, can be further applied.
Q: When these materials are used in practice, what is the feedback from customers? Do they require frequent maintenance and replacement?
The structure of the strip and all aspects of the problem are constantly improving and are much stronger than before. There needs to be a solution to the encapsulation of the strip. The structure of the strip itself is quite complex, but if it is encapsulated well, there is no problem in using it. Another problem is that the current temperature is, after all, in the liquid nitrogen temperature zone, from low temperature to room temperature; there is the problem of thermal stress; all of these need to be strip manufacturers and applications to docking. Slowly actually, many problems have been solved.
Q: What are the constraints on capacity expansion?
It is mainly the problem of process equipment. Now manufacturers are processing outside; many things are designed independently, without their manufacturers. Capacity expansion has to be improved with new equipment.
The level of strip made by manufacturers is now around 100 amperes (a four-millimeter-wide strip), but the intrinsic properties of the strip are very high, and the lab can do 300 or 500. manufacturers are in the process of improvement, and there is a lot of R&D work in it.
Q: Is the whole improvement still in the material’s doping and ratio of elements?
Yes. Including nuclear fusion, induction heating has higher requirements for low-temperature performance; the low-temperature performance of Dongchao strips is better, while Shanghai Superconductors and Shangchuang Superconductors because the process is not the same to improve the low-temperature performance, is more difficult.
Q: How sensitive are users to price?
In the electric power field, we care about the cost, but in the nuclear fusion and MRI fields, we don’t care about the cost so much. Induction heating is a cost-sensitive field but still lower than traditional methods.
Q: When do you think the cost of superconducting materials will be low enough to usher in rapid commercialization?
The cost of superconducting materials is now under 100 dollars, and the number of people using them is already increasing. If the cost is under 50 now, it’s doable. It’s going to be under 50 soon, too.
Q: Which markets will have more demand? What’s the approximate volume?
I have yet to study this in detail, but the demand for materials for nuclear fusion will probably be higher in the next few years.
Q: What is nuclear fusion mainly used for?
Just energy to make fusion reactors.
Q: When do you think commercial cables will be developed?
It may take the state to push this. From the business side, Shanghai Superconductor has proved that this is still better regarding energy saving. But for the State Grid, cable industry safety and stability are the first; yttrium barium copper oxygen is now facing the biggest problem, the low-temperature problem; if the low-temperature refrigeration system can be done very reliably, then the development of superconducting cables should be very fast.
Q: So, low-temperature superconductivity is more costly?
Yes. That’s why this room-temperature superconductivity is so significant. The grid is not active because it’s not clear what the refrigeration system does, and it doesn’t trust superconducting cables.
Q: Are all the refrigeration systems now using liquid nitrogen?
Yes. The superconductors in Shanghai are soaked in liquid nitrogen. Still, due to problems with the connectors and resistors, liquid nitrogen evaporates, so they have been followed by a refrigeration machine to compensate for the evaporated liquid nitrogen.
Q: I read on the internet that a lab will verify the results of this experiment in Korea by the end of this week. Is this true?
If it’s fast, it might come out by the end of the week, but it’s a challenge. The materials will take about two weeks to be made, the same as in Korea.
Q: If the material is made, can it be used for R&D in China?
Even if it does work, the possibility of applying this material to power and fusion is relatively low. This system is now related to applying the parameter. I am still looking for good data. I can only make a judgment once the intrinsic performance data are available.
Q: What is the equipment for producing strips in China?
Low-temperature superconductivity adopts the melting method, that is, melting furnace; high-temperature superconductivity is also similar to this method, but it is the method of powder loading tube; yttrium-barium-copper-oxygen This system of materials is mainly used to do the coating, do the thin film method.
Q: These devices do not constitute a constraint?

The front equipment does not constitute a constraint because it is also more traditional; yttrium-barium-copper-oxygen equipment is still more critical, and each has its own “know-how”, which requires a lot of key technologies.

Chinese Academy of Sciences Discovered the
Root Cause of the False Appearance of Room Temperature Superconducting
Materials: Copper Sulfide Impurity

According to surging news reports, a recent
preprint paper published on the arXiv website by a research team from the
Chinese Academy of Sciences may have ended “LK-99 is a room temperature
superconductor”. This paper not only indicates that the room temperature
superconductivity of LK-99 is a false phenomenon but also finds that the reason
is copper sulfide impurities.

In addition, research teams from
institutions such as the Center for Quantum Materials Science at Peking
University and Princeton University in the United States also submitted
preprinted papers stating that although they observed that their “fired”
LK-99 samples did not exhibit superconductivity and were more like magnets
rather than room temperature superconductors. On August 9, Luo Jianlin, one of
the correspondence authors of the paper mentioned above and a researcher and
doctoral supervisor of the Institute of Physics of the Chinese Academy of
Sciences, told Pengpai Technology that our work pointed out the reason for
mistakenly recognizing LK-99 as a superconductor. “The experimental
results show that (LK-99 can conduct superconductivity at atmospheric pressure
and room temperature) is a fake, originating from cuprous sulfide.”
“LK-99 is not superconducting! Although the relevant samples have weak
diamagnetism, they do not have complete diamagnetism, and there is no zero-resistance



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