• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.2
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• pp.61-70
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• 2023

This paper examines the way of thinking and limitations of physicists regarding the phenomenon of superconductivity and outlines how room-temperature and ambient-pressure superconductors can be developed through the statistical thermodynamic background of the liquid state theory. In hypothesis, the number of electron states should be limited by confining them to a state close to one-Dimension. Simultaneously, the electron-electron interactions should be frequent enough for the electrons to have liquid-like properties. As an example of implementing the hypothesis, our team reports the development of room-temperature and ambient-pressure superconductivity of a material named LK-99 (superconducting compound name developed in the research), whose structure was revealed through numerous experiments with a clue found by chance. Moreover, we summarize the theoretical and experimental basis for the characteristics and discovery of the world's first superconducting material surpassing the critical temperature of 97℃ at atmospheric pressure.

• Progress in Superconductivity and Cryogenics
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• v.25 no.4
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• pp.10-13
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• 2023

To confirm the room-temperature superconductivity at ambient pressure as claimed in recent arXiv preprints by Lee et al., we followed the original authors' systematic solid-state synthesis recipe to reproduce Cu-doped Pb-apatite, known as LK-99. Using X-ray diffraction and Raman spectroscopy, we identified inclusion of various impurities alongside the apatite phase in our sample. While the sample exhibited an overall semiconducting behavior in electrical transport, an intriguing resistivity anomaly at 380 K was observed, possibly originating from a structural phase transition of the Cu_2-δS impurity. Based on the transport and magnetization measurements, we conclude that the sample is a non-magnetic semiconductor, with absence of superconductivity.

• Progress in Superconductivity and Cryogenics
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• v.26 no.2
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• pp.5-8
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• 2024

Recently, Lee et al. claimed that LK-99 isthe first room-temperature superconductor at ambient pressure, which quickly captured the attention of both the scientific community and the general public. We tried to replicate Pb_10-xCu_x(PO₄)₆O, called as LK-99, and characterized its physical properties by measuring the electrical resistance and Meissner effect. The electrical resistance results for different batches exhibited structural phase transitions at different temperatures, and the magnetic measurements indicated weak diamagnetism at 300 K, which is weaker than that of water. Taken together with the structural analysis, these results suggest that the resistivity transitions are incurred by Cu-S compound generated as a byproduct during the synthesis of LK-99 and LK-99 is not a room-temperature superconductor.