Where did the miracle superconductor come from at room temperature?
The new material, called LK-99, was first learned on July 22 with the publication of a preprint of a scientific paper, with its announcement on the arxiv.org service. The team of authors was headed by Lee Sukbae, a previously almost unknown physicist from the Korea Quantum Energy Research Center (QSERF). The scientists claimed that the LK-99 they bought behaves like a superconductor at room temperature and normal pressure, that is, it can pass current through itself without resistance, loss and heating. If confirmed, this discovery would promise a real revolution in all branches of electronics, and even the Nobel Prize in physics or chemistry would not be a sufficient reward for its authors. All superconductors in use today require either liquid nitrogen or helium cooling, or millions of atmospheres of pressure. Fulfilling any of these conditions requires expensive and complex equipment, and therefore superconductors are only used in rare pieces of equipment such as MRI machines.
It is especially important that LK-99 is an inexpensive material that can be synthesized from common raw materials in an ordinary chemistry laboratory. This requires lead oxide, lead sulfate, copper and phosphorus, and the output should be a compound of lead oxide and lead phosphate with the formula Pb.10xcux(P.O.4)6The synthesis described by O. Koreans is easy to carry out on an industrial scale, so LK-99 really had a chance to replace copper in many household appliances. This will make it possible, for example, to get rid of losses in power networks, to create much more powerful compact electric motors, to reduce the cost of MRI machines many times over, and to make trains – maglevs – flying on a magnetic pillow. ordinary
Despite dozens and hundreds of millions of views on the news about the LK-99, physicists viewed the discovery with extreme skepticism. The new superconductor was unlike any similar material known before, it behaved oddly even in the authors’ experiments, and the reaction equations contained major errors. Finally, this study was not published in a peer-reviewed journal, it was simply made available to a free service. At the Institute of Physics named after PN. The Lebedev Academy of Sciences (FIAN) decided to check whether the LK-99 could actually transmit current without loss.
How was the LK-99 tested?
The problem arose even before the experiment started. According to experts from the Center for High-Temperature Superconductivity and Quantum Materials, named after the VI. VL Ginzburg FIAN, if you take the raw materials described by the Koreans and repeat the synthesis procedures, you will get a material with a different formula than indicated in the article. Therefore, the test was carried out in two ways.
In one series of experiments, the recipe described by the Koreans was reproduced exactly, while in the other a substance was obtained with the final formula indicated, but by the correct method. To do this, we had to change the raw materials and the course of the reaction. As a result, the scientists obtained two samples similar to each other – dark anthracite polycrystals. At the same time, the material obtained according to the Korean recipe consisted of two fractions – together with polycrystalline a green glassy mass was formed, which the authors of the invention did not mention at all. Since nothing similar appeared in the photographs of the Korean sample, Russian experts simply cleaned the material for it.
To measure the resistance of the material, four contacts were fixed on the samples: current was passed at the two ends and the voltage between the two centers was measured. If the material were a superconductor, the voltage between the two points would be zero. Two versions of the LK-99 were housed in a cryostat (“freezer”) with a built-in magnet – a strong magnetic field suppresses superconductivity as a result of which it only occurs at a lower temperature. Observation of this phenomenon is considered additional evidence for the discovery of superconductors.
“The experiment showed that the Korean “superconductor” is actually an insulator. You introduce a current there and nothing happens. Also, we started the experiments at room temperature (23 °C), with superconductivity recorded at temperatures of 125 °C and below, according to the development’s authors. The samples went to negative temperatures. “If it is cooled, the resistance (and thus conditionally infinite) only increases. In terms of electrical properties, the LK-99 is similar to the porcelain from which industrial insulators are made.”
Kirill Pervakov, one of the center’s scientists, told socialbites.ca.
In this case, the material samples obtained in the two ways behave almost identically. They do not react to a magnet, whereas superconductors must always repel the magnet and act like a perfect diamagnet.
Physicists performed an X-ray diffraction analysis of the LK-99; this allows you to find out exactly how atoms are positioned in a crystal and what material they are dealing with. To the surprise of experts, the results of the study of both samples nearly matched the data given by the Korean authors. In other words, while Lee Sukbae and his colleagues actually performed a similar synthesis, some scientists suspected that they were completely wrong.
Could the Russian physicists be wrong?
Scientists have serious complaints about the quality of articles by Korean authors. Their explanation is poor and incomplete (in the scientific world this is always the fault of the authors), and therefore FIAN is not prepared to vouch for their exact reproduction of the experiment. Chinese researchers from Huazhong University of Science and Technology also tried to reproduce the LK-99 using the method described in the original article. They didn’t measure the resistance of the resulting sample, they just checked if it was diamagnetic. It turned out that one of the purer grains of the resulting sample, better alloyed with copper, showed diamagnetic properties at temperatures above 100 °C and could almost levitate in a magnetic field (raising and resting on the table). edge). However, pyrolytic graphite is not a superconductor, but is also capable of magnetic levitation in very strong fields. even living frogs fly into the air.