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LK-99 is a proposed ambient pressure and room-temperature superconductor with a gray‒black appearance. LK-99 has a hexagonal structure slightly modified from lead‒apatite and functions as a superconductor at 400 K (127 °C; 260 °F).

The chemical composition of LK-99 is approximately Pb₉Cu₁(PO₄)₆O such that—compared to pure lead-apatite (Pb₁₀(PO₄)₆O)—approximately one quarter of Pb(2) ions are replaced by Cu(II) ions. This partial replacement of Pb ions (measuring 133 picometre) with Cu ions (measuring 87 picometre) causes a 0.48% reduction in volume, creating internal stress inside the material..

The internal stress causes a heterojunction quantum well between the Pb(1) and oxygen within the Phosphate () generating a superconducting quantum well (SQW). LK-99 exhibits a response to a magnetic field (Meissner effect) when chemical vapor deposition is used to apply LK-99 to non-magnetic copper sample. Pure lead-apatite is an insulator, but the copper-dopped lead-apatite forming LK-99 is a superconductor, or at higher temperatures, a metal.

The material was investigated by a team of Sukbae Lee et al from the Korea Institute of Science and Technology (KIST).

Synthesis

Sukbae Lee et al synthesised the LK-99 material by production of Lanarkite by 50%/50% mixing of Lead(II) oxide (PbO) and Lead(II) sulfate (Pb(SO₄)) powders then heating at 725 °C (1,000 K; 1,340 °F) for 24 hours in the presence of air:

Pb₂(SO₄)O = PbO + Pb(SO₄)

Additionally, Copper(I) phosphide (Cu₃P) was produced by mixing Copper (Cu) and Phosphorus (P) powders, in a sealed tube at a vacuum at 10 torr and heated to 550 °C (820 K; 1,000 °F) for 48 hours:

Cu₃P = Cu + P

Lanarkite and Copper phosphide crystals were ground into a powder, mixed and placed in a sealed tube at a vacuum of 10 torr and heated to 925 °C (1,200 K; 1,700 °F) for between 5‒20 hours where (0.9<x<1.1):

Pb_10-xCu_x(PO₄)₆O + S = Pb₂(SO₄)O + Cu₃P

Name

The name LK-99 is from the initials of the two discovers Dr. Lee, and Dr. Kim, and the year of discovery (1999). A patent application was filed in 2021 and granted on 3 March 2023. A Korean trademark application for "LK-99" was filed on 4 April 2023 by the Quantum Energy Research Centre.

References

1. ^ Lee, Sukbae; Kim, Ji-Hoon; Kwon, Young-Wan (2023-07-22). "The First Room-Temperature Ambient-Pressure Superconductor". arXiv:2307.12008.
2. Lee, Sukbae; Kim, Ji-Hoon; Im, Sungyeon; An, Soomin; Kwon, Young-Wan; Ho, Auh Keun (2023-03-31). "Consideration for the development of room-temperature ambient-pressure superconductor (LK-99)". Korean Crystal Growth and Crystal Technology. 33 (2). Korea Association Of Crystal Growth: 61‒70. doi:10.6111/JKCGCT.2023.33.2.061.
3. ^ Lee, Sukbae; Kim, Ji-Hoon; Kim, Hyun-Tak; Im, Sungyeon; An, SooMin; Auh, Keun Ho (2023-07-22). "Superconductor Pb_10−xCu_x(PO₄)₆O showing levitation at room temperature and atmospheric pressure and mechanism". arXiv:2307.12037.
4. Kim, Ji-Hoon. "About". Retrieved 2023-07-26. working on superconducting materials again, and finally, succeeded in synthesizing a room temperature and atmospheric pressure superconductor (RTAP-SC) … named LK99 (first discovered as a trace by Dr. Lee and Dr. Kim in 1999).
5. KR published 2023027536A1, 이석배; 김지훈 & 권영완, "Ceramic composite with superconductivities over room temperature at atmospheric condition and method of manufacturing the ceramic composite", published 2023-03-02 
6. LK-99. Korea Intellectual Property Rights Information Service (Report). Korean Intellectual Property Office. 2023-04-04. LK-99; … Applicant: Quantum Energy Research Centre (Q-centre); … Status: Awaiting Examination

External links

• Magnetic Property Test of LK-99 Film (video). Quantum Energy Research Centre. 2023-01-26. Retrieved 2023-07-25 – via Youtube.
• Kim, Hyun-Tak (2023-07-25). Superconductor Pb_10-xCu_x(PO₄)₆O showing levitation at room temperature and atmospheric pressure and mechanism (video). Retrieved 2023-07-25 – via ScienceCast.

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