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'''LK-99''' is a claimed [[ambient pressure]] and [[room-temperature superconductor]] with a gray‒black appearance.{{r|sukbae-2023|p=8}}
'''LK-99''' is a proposed [[ambient pressure]] and [[room-temperature superconductor]] with a gray‒black appearance.{{r|sukbae-2023|p=8}}
LK-99 has a hexagonal structure slightly modified from [[lead]]‒[[apatite]] and is claimed to function as a superconductor below {{convert|400|K|C F|lk=in}}.{{r|sukbae-2023b}}{{r|sukbae-2023|p=1}}
LK-99 has a hexagonal structure slightly modified from [[lead]]‒[[apatite]] and is claimed to function as a superconductor below {{convert|400|K|C F|lk=in}}.{{r|sukbae-2023b}}{{r|sukbae-2023|p=1}}
The material was investigated by a team of Sukbae Lee, Ji-Hoon Kim, ''et al.'' from the [[Korea Institute of Science and Technology]] (KIST).{{r|sukbae-2023|p=1}} {{As of|2023|7|26}} the discovery of LK-99 superconductivity has not been [[peer review]]ed or independently [[Reproducibility|replicated]].{{r|flaherty-20230626}}
The material was investigated by a team of Sukbae Lee, Ji-Hoon Kim, ''et al.'' from the [[Korea Institute of Science and Technology]] (KIST).{{r|sukbae-2023|p=1}} {{As of|2023|7|26}} the discovery of LK-99 superconductivity has not been [[peer review]]ed or independently [[Reproducibility|replicated]].{{r|flaherty-20230626}}
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== Response ==
== Response ==
{{As of|2023|07|26}}, the measured properties do not prove that LK-99 is a superconductor as they do not fully explain how the LK-99's magnetisation can change, nor its specific heat capacity.{{r|padavic-c-20230726}}
Media reports on the reported discovery mentioned the concurrent retractions of fraudulent research on high temperature superconductors by [[Ranga P. Dias]]. Scientists speculated that the material could be strongly [[Diamagnetism|diamagnetic]], but perhaps not [[Superdiamagnetism|diamagnetic enough]] to become a superconductor.{{r|ritchie-20230726}}

An alternative explanation for LK-99's stated reaction to magnets could be [[diamagnetism]].{{r|ritchie-20230726}}


==References==
==References==

Revision as of 07:25, 28 July 2023

LK-99
Identifiers
3D model (JSmol)
  • InChI=1S/Cu.6H3O4P.O.9Pb/c;6*1-5(2,3)4;;;;;;;;;;/h;6*(H3,1,2,3,4);;;;;;;;;;/q+2;;;;;;;-2;9*+2/p-18
    Key: KZSIWLDFTIMUEG-UHFFFAOYSA-A
  • [Pb+2].[Pb+2].[Pb+2].[Pb+2].[Pb+2].[Pb+2].[Pb+2].[Pb+2].[Pb+2].[Cu+2].O=P([O-])([O-])[O-].O=P([O-])([O-])[O-].O=P([O-])([O-])[O-].O=P([O-])([O-])[O-].O=P([O-])([O-])[O-].O=P([O-])([O-])[O-].[O-2]
Properties
CuO25P6Pb9
Molar mass 2514.2 g·mol−1
Appearance grey black solid
Structure
hexagonal
P63/m
176
a = 9.843 Å, c = 7.428 Å
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

LK-99 is a proposed ambient pressure and room-temperature superconductor with a gray‒black appearance.[1]: 8  LK-99 has a hexagonal structure slightly modified from lead‒apatite and is claimed to function as a superconductor below 400 K (127 °C; 260 °F).[2][1]: 1  The material was investigated by a team of Sukbae Lee, Ji-Hoon Kim, et al. from the Korea Institute of Science and Technology (KIST).[1]: 1  As of 26 July 2023 the discovery of LK-99 superconductivity has not been peer reviewed or independently replicated.[3]

Chemical composition

The chemical composition of LK-99 is approximately Pb9Cu(PO4)6O such that—compared to pure lead-apatite (Pb10(PO4)6O)[4]: 5 —approximately one quarter of Pb(II) ions in position 2 of the apatite structure are replaced by Cu(II) ions.[1]: 9  This partial replacement of Pb2+ ions (measuring 133 picometre) with Cu2+ ions (measuring 87 picometre) is said to cause a 0.48% reduction in volume, creating internal stress inside the material.[1]: 8 

The internal stress is claimed to cause a heterojunction quantum well between the Pb(1) and oxygen within the phosphate ([PO4]3−) generating a superconducting quantum well (SQW).[1]: 10  Lee et al. claim to show LK-99 exhibits a response to a magnetic field (Meissner effect) when chemical vapor deposition is used to apply LK-99 to a non-magnetic copper sample.[1]: 4  Pure lead-apatite is an insulator, but Lee et al. claim copper-doped lead-apatite forming LK-99 is a superconductor, or at higher temperatures, a metal.[4]: 5 

Synthesis

Sukbae Lee (이석배) and Ji-Hoon Kim (김지훈) provide a method for synthesising LK-99 material[4]: 2  by production of Lanarkite from 1:1 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:

PbO + Pb(SO4) → Pb2(SO4)O

Additionally, copper(I) phosphide (Cu3P) was produced by mixing copper (Cu) and phosphorus (P) powders in a sealed tube under a vacuum of 10-3 torr and heated to 550 °C (820 K; 1,000 °F) for 48 hours:[4]: 3 

Cu + P → Cu3P

Lanarkite and copper phosphide crystals were ground into a powder, mixed in a 1:1 molar ratio, placed in a sealed tube under a vacuum of 10-3 torr, and heated to 925 °C (1,200 K; 1,700 °F) for between 5‒20 hours:[4]: 3 

Pb2(SO4)O + Cu3P + O2 (g) → Pb10-xCux(PO4)6O + S (g), where (0.9 < x < 1.1)

Name

The name LK-99 is from the initials of the two discovers Dr. Lee, and Dr. Kim, and the year of discovery (1999).[5] The pair had originally been working with Professor Choi Dong-Shik (최동식) at Korea University in the 1990s.[6]

The findings were originally submitted to Nature in 2020, but rejected — owing to reservations around Nature's own publication of (falsified) superconductor research by Ranga P. Dias.[6] A patent application was filed in 2021 and published on 3 March 2023.[7] A Korean trademark application for "LK-99" was filed on 4 April 2023 by the Quantum Energy Research Centre.[8] The findings were submitted to APL Materials on 23 July 2023 for review.[6]

Authors

Author credit and affiliation matrix:

Author
Affiliation
 Lee, Sukbae (이석배) Kim, Ji-Hoon (김지훈) Kim, Hyun-Tak (김현탁) Im, Sungyeon (임성연) An, SooMin (안수민) Kwon, Young-Wan (권영완) Auh, Keun Ho (오근호) Choi, Dong-Shik (최동식)
HYU Professor Emeritus
KIST Professor
W&M Professor
Q-Centre (주)퀀텀에너지연구소 CEO R&D Dir. checkY checkY CTO checkY
Patent (2020)[9] 1 2
Patent (2021)[7] 1 2 3
Lee & Kim+ (2023a)[2] 1 2 3 4 5 6 Acknowledged
Lee & Kim+ (2023b)[1] 1 2 Acknowledged Acknowledged 3 Acknowledged
Lee & Kim+ (2023c)[4] 1 2 3 4 5 Acknowledged 6 Acknowledged

Response

As of 26 July 2023, the measured properties do not prove that LK-99 is a superconductor as they do not fully explain how the LK-99's magnetisation can change, nor its specific heat capacity.[10]

An alternative explanation for LK-99's stated reaction to magnets could be diamagnetism.[11]

References

  1. ^ a b c d e f g h Lee, Sukbae; Kim, Ji-Hoon; Kwon, Young-Wan (22 July 2023). "The First Room-Temperature Ambient-Pressure Superconductor". arXiv:2307.12008.
  2. ^ a b Lee, Sukbae; Kim, Ji-Hoon; Im, Sungyeon; An, Soomin; Kwon, Young-Wan; Auh, Keun Ho (31 March 2023). "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. Archived from the original on 25 July 2023. Retrieved 25 July 2023.
  3. ^ Flaherty, Nick (26 July 2023). "Race is on for room temperature superconductor". Technology News. eeNews Europe. European Business. Archived from the original on 26 July 2023. Retrieved 26 July 2023. published on the pre-print server arxiv.org and still has to go through peer review
  4. ^ a b c d e f Lee, Sukbae; Kim, Ji-Hoon; Kim, Hyun-Tak; Im, Sungyeon; An, SooMin; Auh, Keun Ho (22 July 2023). "Superconductor Pb10−xCux(PO4)6O showing levitation at room temperature and atmospheric pressure and mechanism". arXiv:2307.12037.
  5. ^ Kim, Ji-Hoon. "About". Retrieved 26 July 2023. 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).
  6. ^ a b c 이병철; 최정석 (27 July 2023). "'노벨상감' 상온 초전도체 세계 최초 개발했다는 한국 연구...과학계 '회의론' 넘을까" [Korean study into world's first room-temperature superconductor … can it overcome scientific 'skepticism' … to win Nobel prize]. Chosun Biz (in Korean). Archived from the original on 27 July 2023. Retrieved 27 July 2023. 연구를 주도한 이석배 퀀텀에너지연구소 대표는 27일 오전 조선비즈와 만나 "2020년에 처음 연구 결과를 네이처에 제출했지만 다이어스 교수 사태 때문에 네이처가 논문 게재를 부담스러워했고, 다른 전문 학술지에 먼저 게재할 것을 요구했다"며 "국내 학술지에 먼저 올려서 국내 전문가의 검증을 받고 사전공개 사이트인 아카이브에 올린 것"이라고 말했다. 이 대표는 지난 23일 국제 학술지인 'ALP 머터리얼즈'에도 논문을 제출했다고 덧붙였다. 세계적인 물리학 저널에 인정을 받겠다는 설명이다. … "지금은 작고한 최동식 고려대 화학과 교수와 함께 1990년대 중반부터 상온 초전도체 구현을 위해 20년에 걸쳐 연구와 실험을 진행했다"고 말했다. 이 대표는 상압상온 초전도체에 대한 특허도 출원했다고 밝혔다.
  7. ^ a b 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  Archived 2023-07-26 at the Wayback Machine
  8. ^ LK-99. Korea Intellectual Property Rights Information Service (Report). Korean Intellectual Property Office. 4 April 2023. Archived from the original on 26 July 2023. Retrieved 25 July 2023. LK-99; … Applicant: Quantum Energy Research Centre (Q-centre); … Status: Awaiting Examination
  9. ^ KR application 20210062550A, 이석배 & 김지훈, "Method of manufacturing ceramic composite with low resistance including superconductors and the composite thereof", published 2022-06-02 
  10. ^ Padavic-Callaghan, Karmela (26 July 2023). "Room-temperature superconductor 'breakthrough' met with scepticism". New Scientist. Archived from the original on 26 July 2023. Retrieved 26 July 2023.
  11. ^ Ritchie, Stuart (26 July 2023). "The latest mega-breakthrough on room-temperature superconductors is probably nonsense". i. Archived from the original on 26 July 2023. Retrieved 27 July 2023.

Further reading

Retrieved from "https://en.wikipedia.org/w/index.php?title=LK-99&oldid=1167521503"