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LK-99

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LK-99

3D structure
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
Density ≈6.699 g/cm3[1]
Structure
hexagonal
P63/m, No. 176
a = 9.843 Å, c = 7.428 Å
623.2 Å3
1
Related compounds
Related compounds
 Oxypyromorphite (lead apatite)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

LK-99 is a potential room-temperature superconductor with a gray‒black appearance.[2]: 8  It has a hexagonal structure slightly modified from lead‒apatite, by introducing small amounts of copper. The material was first discovered and manufactured by a team of researchers including Sukbae Lee (이석배), and Ji-Hoon Kim (김지훈) from Korea University (KU).[2]: 1  The team claims it functions as a superconductor at ambient pressure and below 400 K (127 °C; 260 °F).[3][2]: 1 

As of 31 July 2023, the material has not been confirmed to be superconducting at any temperature. The synthesis of LK-99 and observation of its superconductivity has not been peer reviewed or independently replicated.[4] The announcement was widely shared and the reaction by the scientific world was mainly skeptical due to the extraordinary nature of the claims,[5] and errors and inconsistencies in the pre-published papers. Independent teams are attempting to replicate the South Korean team's work, with results expected in August 2023 owing to the straightforward method of producing the material.[5]

The initial studies announcing the discovery were uploaded to arXiv. Lee claimed that the uploaded preprint papers were incomplete,[6] while coauthor Hyun-Tak Kim (김현탁) stated that one of the papers contained defects.[7]

Chemical properties

The chemical composition of LK-99 is approximately Pb9Cu(PO4)6O such that—compared to pure lead-apatite (Pb10(PO4)6O)[8]: 5 —approximately one quarter of Pb(II) ions in position 2 of the apatite structure are replaced by Cu(II) ions.[2]: 9 

Synthesis

Lee et al. provide a method for chemical synthesis of LK-99 material[8]: 2  by producing lanarkite from a 1:1 molar 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.:

PbO + Pb(SO4) → Pb2(SO4)O

Additionally, copper(I) phosphide (Cu3P) was produced by mixing copper (Cu) and phosphorus (P) powders in a 3:1 molar ratio in a sealed tube under a vacuum and heated to 550 °C (820 K; 1,000 °F) for 48 hours:[8]: 3 

Cu + P → Cu3P

Lanarkite and copper phosphide crystals were ground into a powder,, placed in a sealed tube under a vacuum, and heated to 925 °C (1,200 K; 1,700 °F) for between 5‒20 hours:[8]: 3 

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

Physical properties

(a) Diamagnetic susceptibility measurements of LK-99, (b) sample of LK-99 partially levitating over large magnet

The material is claimed to be a room-temperature superconductor.[8]: 1  An article shows the material exhibiting strong diamagnetic properties, with a published video depicting a sample of the material partially levitating on top of a large magnet.[8]

Proposed mechanism for superconductivity

Partial replacement of Pb2+ ions (measuring 133 picometres) with Cu2+ ions (measuring 87 picometres) is said to cause a 0.48% reduction in volume, creating internal stress inside the material.[2]: 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).[2]: 10 

Lee et al. claim to show LK-99 exhibits a response to a magnetic field (potentially due to the Meissner effect) when chemical vapor deposition is used to apply LK-99 to a non-magnetic copper sample.[2]: 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. [8]: 5  They do not claim to have observed any change in behavior across a transition temperature.[citation needed]

Compound name

The name LK-99 is from the initials of discoverers Lee and JH Kim, and the year of discovery (1999).[9] The pair had originally been working with Professor Tong-Seek Chair (최동식) at Korea University in the 1990s.[10]

In 2008, researchers from Korea University founded the Quantum Energy Research Centre [Q-Centre].[6] Lee would later become CEO of Q-Centre, and Kim would become director of research and development (R&D) at Q-Centre.

When Tong-Seek Chair died in 2017, he requested in his will that LK-99 research be continued. Q-Centre got new funding in the same year and interest in LK-99 research was renewed in 2018.[citation needed]

Publication history

An initial paper was submitted to Nature in 2020, but rejected.[10] Similarly-presented research on room-temperature superconductors by Ranga P. Dias had been published in Nature earlier that year, and received with skepticism—Dias's paper would subsequently be retracted in 2022 after its data was found to have been falsified.[11]

Lee and JH Kim filed a patent application in 2021 which was published on 3 March 2023.[12] A Korean trademark application for "LK-99" was filed on 4 April 2023 by the Q-Centre.[13]

A series of academic publications summarizing initial findings came out in 2023, with a total of seven authors across four publications. The first publication appeared on arXiv on 22 July, listing Young-Wan Kwon, former Q-Centre CTO, as third author. A second preprint listed as third author Hyun-Tak Kim, former principal researcher at the Electronics & Telecommunications Research Institute and professor at the College of William & Mary.

The findings were submitted to APL Materials on 23 July 2023 for peer review.[10][6]

On 28 July 2023 Kwon presented the findings of the group at a symposium held at Korea University.[14][15][16] That same day, Yonhap News Agency published an article quoting an official from Korea University as saying that Kwon was no longer in contact with the University.[6] The article also quoted Lee saying that Kwon had left the Q-Centre Research Institute four months previously;[6] that the academic papers on LK-99 were not finished; and that the papers had been uploaded to arXiv without the other authors' permission.[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) Chair, Tong-Seek (최동식)
HYU Professor Emeritus
KU‒KIST former Research Professor[6]†
W&M Professor
Q-Centre (주)퀀텀에너지연구소 CEO R&D Director checkY checkY former CTO[6] checkY
Patent (2020)[17] 1 2
Patent (2021)[12] 1 2 3
Lee & Kim+ (2023a)[3] 1 2 3 4 5 6 Acknowledged
Lee & Kim+ (2023b)[2] 1 2 Acknowledged Acknowledged 3 Acknowledged
Lee & Kim+ (2023c)[8] 1 2 3 4 5 Acknowledged 6 Acknowledged

("1" = first author, "2" = second author, etc.)

Response

Materials scientists and superconductor researchers responded with skepticism.[7] The highest-temperature superconductors known at the time of publication had a critical temperature of 250 K (−20 °C; −10 °F) at pressures of over 170 gigapascals (1,700,000 atm; 25,000,000 psi). The highest-temperature superconductors at atmospheric pressure (1 atm) had a critical temperature of at most 150 K.

As of 31 July 2023, the measured properties do not prove that LK-99 is a superconductor as the published material does not fully explain how the LK-99's magnetisation can change, demonstrate its specific heat capacity, or demonstrate it crossing its transition temperature.[7] An alternative explanation for LK-99's stated partial magnetic levitation could be solely from non-superconductive diamagnetism.[18]

Replication attempts

As of July 2023, the experiment has not been sucessfully replicated, despite the initial experiments being completed in 2020. After the July 2023 publications release, independent groups reported that they had begun attempting to reproduce the synthesis. The results of those independent tests are expected within weeks.[5]

Group Country Status Best result References Notes
Argonne National Laboratory  United States Unknown N/A [19]
Collège de France - Solid State Chemistry and Energy Lab  France Unknown N/A [20][21][22][original research] PHD student on twitter.

Account from 2017.

Council Of Scientific And Industrial Research - National Physical Laboratory of India (CSIR-NPLI)  India Complete Failure [23][24][25][26][27]
University of Maryland - Condensed Matter Theory Center  United States Unknown N/A [28] it's the official twitter account.[29]
Nanjing University  China Unknown N/A [30]
Southeast University  China Complete Failure [31][32][original research]

References

  1. ^ "2514.2 AMU /(sin(60°)*9.843*9.843*7.428 Å^3)". WolframAlpha (calculation). Archived from the original on 29 July 2023. Retrieved 29 July 2023.
  2. ^ 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.
  3. ^ 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.
  4. ^ 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
  5. ^ a b c Garisto, Dan (27 July 2023). "Viral New Superconductivity Claims Leave Many Scientists Skeptical". Materials science. Scientific American. Archived from the original on 27 July 2023. Retrieved 28 July 2023.
  6. ^ a b c d e f g h 조승한 (28 July 2023). 강의영 (ed.). '상온 초전도체 구현' 한국 연구에 국내외 논란…"검증 거쳐야" [Controversy both domestic and abroad regarding Korean development of room temperature superconductor … "It has to be verified"] (in Korean). Yonhap News Agency. Archived from the original on 28 July 2023. Retrieved 28 July 2023. … 논문이 아니며 공개도 의도한 바가 아니라고 선을 그었다. … 이 대표는 이날 연합뉴스와 통화에서 "다른 저자들의 허락 없이 권 연구교수가 임의로 아카이브에 게재한 것"이라며 "아카이브에 내려달라는 요청을 해둔 상황" 이라고 주장했다. … 이 대표는 권 연구교수가 퀀텀에너지연구소 최고기술책임자(CTO)로 있었지만 4개월 전 이사직을 내려놓고 현재는 회사와 관련이 없다고도 밝혔다. … 고려대 관계자에 따르면 권 연구교수는 현재 학교와도 연락이 닿지 않는 상황으로 알려졌다.
  7. ^ a b c 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. Speaking to New Scientist, Hyun-Tak Kim at the College of William & Mary in Virginia says he will support anyone trying to replicate his team's work. … [HT] Kim has only co-authored one of the arXiv papers, while the other is authored by his colleagues at the Quantum Energy Research Centre in South Korea, … Both papers present similar measurements, however Kim says that the second paper contains "many defects" and was uploaded to arXiv without his permission. In that paper, the work is described as opening a "new era for humankind" … Once the findings are published in a peer-reviewed journal, which [HT] Kim says is in the works, he will support anyone who wants to create and test LK-99 for themselves. In the meantime, he and his colleagues will continue to work on perfecting their samples of the alleged miracle superconductor and move towards mass-producing it.
  8. ^ a b c d e f g h 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.
  9. ^ 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).
  10. ^ 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.
  11. ^ Garisto, Dan (25 July 2023). "'A very disturbing picture': another retraction imminent for controversial physicist". Nature. doi:10.1038/d41586-023-02401-2. Archived from the original on 27 July 2023. Retrieved 28 July 2023.
  12. ^ 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
  13. ^ 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
  14. ^ Kwon, Young-Wan (28 July 2023). The World First: Room-Temperature Ambient-Pressure Superconductor. MML 2023: 11th International Symposium on Metallic Multilayers (conference presentation). Korea University, Seoul, Korea: The Korean Magnetics Society.
  15. ^ Seifert, Tom S. [@TeraTom_S] (28 July 2023). "Just listening to an impressive talk of one of the coauthors of the room-temperature superconductor #LK99 at Korea university, Young-Wan Kwon. Just one of the great experiences of the MML2023 conference in Seoul. #MML23" (Tweet). Retrieved 28 July 2023 – via Twitter.
  16. ^ Bodin, Kenneth [@KennethBodin] (28 July 2023). "They have now also presented at MML2023. They took questions. Answers not entirely satisfying. Rumour is that MIT SC specialists are flying over to scrutinize experiments. (Photo @JohanaAkerman [Johaa Akerman])" (Tweet). Retrieved 28 July 2023 – via Twitter.
  17. ^ KR application 20210062550A, 이석배 & 김지훈, "Method of manufacturing ceramic composite with low resistance including superconductors and the composite thereof", published 2022-06-02 
  18. ^ 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. What about that levitation video? Dr Sven Friedemann, associate professor at the University of Bristol's School of Physics, told i that it, and other data in the paper, "could stem from other phenomena". Graphene, … "is also diamagnetic [displaying repulsion like a superconductor] and can produce weak levitation". The video, in other words, could have a non-superconductor explanation.
  19. ^ "A spectacular superconductor claim is making news. Here's why experts are doubtful". Archived from the original on 29 July 2023. Retrieved 29 July 2023.
  20. ^ "https://twitter.com/zoubairezzz0595/status/1686045967139602432". Twitter. Retrieved 31 July 2023. {{cite web}}: External link in |title= (help)
  21. ^ "zoubair (@zoubairezzz0595)". Nitter. Retrieved 31 July 2023.
  22. ^ "PhD students". Solid-State Chemistry and Energy Lab. 12 September 2019. Retrieved 31 July 2023.
  23. ^ "Dr. V.P.S. Awana, PhD - Editorial Board - Superconductivity - Journal - Elsevier". www.journals.elsevier.com. Retrieved 31 July 2023.
  24. ^ "People@CSIR-NPL – NPL". Retrieved 31 July 2023.
  25. ^ "Post on facebook". Facebook. Retrieved 31 July 2023.
  26. ^ "Post on facebook". Facebook. Retrieved 31 July 2023.
  27. ^ Kumar, Kapil (31 July 2023). "Synthesis of possible room temperature superconductor LK-99:Pb9Cu(PO4)6O". arXiv:2307.16402.
  28. ^ "https://twitter.com/condensed_the/status/1685291727307808769". Twitter. Retrieved 31 July 2023. {{cite web}}: External link in |title= (help)
  29. ^ "Condensed Matter Theory Center". www.physics.umd.edu. Retrieved 31 July 2023.
  30. ^ "南大教授谈韩国室温超导：不像超导，正重复实验—新闻—科学网". news.sciencenet.cn. Archived from the original on 31 July 2023. Retrieved 31 July 2023.
  31. ^ "-东南大学超导物理小组". www.scseu.cn. Retrieved 31 July 2023.
  32. ^ 科学调查局. "室温超导复现实验-全流程_哔哩哔哩_bilibili". www.bilibili.com (in Simplified Chinese). Retrieved 31 July 2023.

Further reading

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