On December 13, 2023, the Verification Committee of the Korean Society for Superconductivity and Low Temperature released a scientific assessment of the LK-99 room temperature superconductor incident that caused a sensation in July this year. It is pointed out that after comprehensive consideration of the original data and the results of reproduction experiments at home and abroad, there is no evidence to prove that LK-99 is a superconductor at room temperature and pressure, but an insulator containing a large number of impurities, and its so-called superconductivity is only an illusion caused by the electrical and magnetic effects of impurities.
LK-99 is a compound composed of copper, lead, phosphorus and oxygen, and its structure is similar to that of lead apatite. In July of this year, Sook-baek Lee and Ji-hoon Kim of the Korea Center for Quantum Energy published an article on the preprint platform ARXIV, claiming that they had successfully synthesized LK-99 and discovered its superconductivity at atmospheric pressure and at a temperature of at least 127 (400K). They also provided a segment** showing that the LK-99 sample was able to levitate on a magnet, exhibiting the Meissner effect of superconductors. This news has aroused widespread attention and discussion in the international scientific community, because superconductor is a material that can conduct electric current in a state of zero resistance, which has great scientific and technical value, but the currently known superconductors need to be realized at extremely low temperatures or extremely high pressures, and LK-99 will be a major breakthrough if it is really a superconductor at room temperature and pressure.
However, as more and more research teams tried to replicate the synthesis and measurement of LK-99, they found that LK-99 did not exhibit superconductivity, but was an insulator with high resistivity, and its levitation was only due to the ordinary effects of ferromagnetism and diamagnetism, rather than the Meissner effect. After many experiments and theoretical analysis, scientists found that there are a large number of impurities in LK-99, especially copper sulfide, which will undergo phase transformation at a certain temperature, resulting in a sharp drop in resistivity, thus misleading the judgment of the original author. In addition, the structure of LK-99 is also not conducive to the generation of superconductivity because its electrons are strongly localized and cannot form superconducting electron pairs.
In order to make an authoritative evaluation of the LK-99 event, the Korean Society for Superconductivity and Cryogenics established a verification committee composed of 10 experts in August to comprehensively consider the original data and the results of reproducible experiments at home and abroad. The committee held that the authors did not provide sufficient evidence to support the superconductivity of LK-99, and the results of the reproduction experiment unequivocally denied the superconductivity of LK-99. The committee also pointed out that the original authors did not follow the basic principles of scientific research, did not fully characterize the samples, did not conduct rigorous analysis of the experimental results, did not rule out possible errors and interferences, did not communicate and cooperate effectively with other research teams, and did not critically reflect on their own conclusions. The Committee called on the original authors to retract as soon as possible, to apologize to the scientific community and the public, and to reflect on their actions.
The committee was supported by the Ministry of Science and Technology of South Korea, which said that the LK-99 incident had caused damage to South Korea's scientific credibility, and also brought confusion and disappointment to the scientific community and the public.
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