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LK-99

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This is an old revision of this page, as edited by Cyp (talk | contribs) at 07:47, 8 August 2023 (→Proposed mechanism for superconductivity: has → may have). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

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 (from the Lee-Kim 1999 research)[2] is a gray-black, polycrystalline compound that is potentially a room-temperature superconductor.[3]: 8  It is said to have a hexagonal structure that is slightly modified from lead‒apatite by adding small amounts of copper. A team from Korea University led by Sukbae Lee (이석배) and Ji-Hoon Kim (김지훈) began studying this material in 1999.[3]: 1  According to their claims, LK-99 acts as a superconductor at temperatures below 400 K (127 °C; 260 °F) and at ambient pressure.[2][4][3]: 1 

As of 7 August 2023, the scientific community has not validated the superconductivity of LK-99 at any temperature through peer-reviewed processes or independent replication by other research groups.[5] One preprint by a team from Southeast University, China has reported an observation of zero resistance at 110 K (-163 ℃, -261 ℉).[6] However the absence of a well-defined phase transition, absence of the Meissner effect (a defining characteristic of superconductors), and the unique conditions under which these results were obtained raised doubts about the validity of the claim. Multiple other independent research teams are currently attempting to replicate the work of the South Korean team. More results are expected in August 2023, as the process of producing the material is said to be straightforward.[7]

The initial studies announcing the discovery of LK-99 were uploaded to arXiv, an open-access repository of electronic preprints. Lee later claimed the uploaded preprint papers were incomplete,[8] and coauthor Hyun-Tak Kim (김현탁) stated that one of the papers contained defects.[9]

Chemical properties and structure

The chemical composition of LK-99 is approximately Pb9Cu(PO4)6O, in which— compared to pure lead-apatite (Pb10(PO4)6O)[10]: 5 — approximately one quarter of Pb(II) ions in position 2 of the apatite structure are replaced by Cu(II) ions.[3]: 9 

The structure is similar to that of apatite, space group P63/m (No. 176).

Synthesis

Lee et al. provide a method for chemical synthesis of LK-99[10]: 2  in three steps. First they produce lanarkite from a 1:1 molar mixing of lead(II) oxide (PbO) and lead(II) sulfate (Pb(SO4)) powders, and heating at 725 °C (1,000 K; 1,340 °F) for 24 hours:

PbO + Pb(SO4) → Pb2(SO4)O.

Then, copper(I) phosphide (Cu3P) is 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:[10]: 3 

3 Cu + P → Cu3P.

Then, lanarkite and copper phosphide crystals are 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:[10]: 3 

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

The above reaction from the initial paper is not balanced, however. A preprint paper by Kapil Kumar et al. reported the presence of copper(I) sulfide (Cu2S) as well.[11] For a balanced reaction might be:

5 Pb2SO4O + 6 Cu3P → Pb9Cu(PO4)6O + 5 Cu2S + Pb + 7 Cu[12]

This is incompatible with sulfur being produced in the tube.[citation needed]

Physical properties

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

Some LK-99 samples have been reported to show strong diamagnetic properties, including partial levitation over a magnet,[10] which is correlated with superconductivity.

While the initial articles claim the material is a room-temperature superconductor,[10]: 1  they do not claim to have seen definitive features of superconductivity, zero resistance and the Meissner effect.

Because many materials can spuriously seem like potential candidates for high-temperature superconductivity,[13] researchers testing for superconductivity generally demonstrate not only a zero-resistance mode and a clear Meissner effect, but also demonstrate other expected properties such as flux pinning, AC magnetic susceptibility, the Josephson effect, a temperature-dependent critical field and current, or a sudden jump in specific heat around the critical temperature.[14] As of 5 August 2023, none of these have been observed by the original experiment or by attempted replications.[15]

Proposed mechanism for superconductivity

While the papers agree that LK-99 may have superconductivity, they make different claims about the mechanism by which it does so. It is unclear whether these claims are related or separate theories.

Electron superfluid and 1-dimension zero-resistance

This is the hypothesis advocated in a paper mainly contributed by Lee and JH Kim. It is in line with the arguments of Chair in the 1990s. Electrons behave like a kind of fluid, and the argument is that superconductivity occurs when electrons behave like a superfluid. Their argument is that superconductivity can be achieved at higher temperatures by constraining the electrons' degrees of freedom, and one-dimensional structure are one way to constrain the electrons' degrees of freedom.[4]

Superconducting quantum well

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.[3]: 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).[3]: 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.[3]: 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.[10]: 5  They do not claim to have observed any change in behavior across a transition temperature.

BR-BCS

Another mechanism is based on a 2021 paper[16] by Hyun-Tak Kim describing a novel "BR-BCS" theory of superconductivity combining a classical theory of metal-insulator transitions[17], the standard Bardeen–Cooper–Schrieffer theory of superconductivity, and ideas from a controversial theory of hole superconductivity[18] by J.E.Hirsch.

On 31 July 2023, Sinéad Griffin of Lawrence Berkeley National Laboratory analyzed LK-99 with density functional theory (DFT), showing that its structure would have correlated isolated flat bands, a possible signature of high-transition-temperature superconductors.[19]

Compound name

The name LK-99 is from the initials of discoverers Sukbae Lee and Ji-Hoon Kim, and the year of discovery (1999).[2] The pair had originally been working with Tong-Seek Chair (최동식) at Korea University in the 1990s.[20]

In 2008, researchers from Korea University founded the Quantum Energy Research Centre (퀀텀 에너지연구소; also known as Q-Centre).[8] Lee would later become CEO of Q-Centre, and Kim would become director of research and development (R&D) at Q-Centre.

Publication history

Lee has stated that in 2020, an initial paper was submitted to Nature, but was rejected.[20] Similarly-presented research on room-temperature superconductors (but a totally different chemical system) 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 questioned as having been falsified.[21]

In 2020, Lee and Ji-Hoon Kim filed a patent application.[22] A second patent application (additionally listing Young-Wan Kwon), was filed in 2021, which was published on 3 March 2023.[23] A WIPO patent was also published on 2 March 2023.[24] On 4 April 2023, a Korean trademark application for "LK-99" was filed by the Q-Centre.[25]

In February 2023, the Q-Centre published a video on YouTube claiming to show the magnetic properties of a thin layer of LK-99 thermally deposited on a copper plate.[26]

Scholarly articles and preprints

A series of academic publications summarizing initial findings came out in 2023, with a total of seven authors across four publications.

On 31 March 2023, a Korean-language paper, "Consideration for the development of room-temperature ambient-pressure superconductor (LK-99)", was submitted to the Korean Journal of Crystal Growth and Crystal Technology.[4] It was accepted on 18 April, but was not widely read until three months later.

On 22 July 2023, two preprints appeared on arXiv. The first was submitted by Young-Wan Kwon, and listed Kwon, former Q-Centre CTO, as third author.[3] The second preprint was submitted by Hyun-Tak Kim, and listed Kim, former principal researcher at the Electronics & Telecommunications Research Institute and professor at the College of William & Mary, as third author, as well as three new authors.[10][27] On 23 July, the findings were also submitted by Lee to APL Materials for peer review.[20][8]

On 28 July 2023, Kwon presented the findings at a symposium held at Korea University.[28][29][30] 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.[8] The article also quoted Lee saying that Kwon had left the Q-Centre Research Institute four months previously;[8] that the academic papers on LK-99 were not finished and contained many defects; and that the papers had been uploaded to arXiv without the other authors' permission.[8][27]

On 31 July 2023, a group led by Kapil Kumar published a preprint on arXiv documenting their replication attempts, which confirmed the structure using X-ray crystallography (XRD) but failed to find diamagnetism or levitation.[11]

On 1 August 2023, a Q-Centre representative told SBS News that the original samples referenced in the paper would be released to the world for verification soon.[31]

On 3 August 2023, the Korean LK-99 Verification Committee requested a high-quality sample from the original research team. However, the team responded that they would only provide the sample once the review process of their paper, potentially submitted to APL Materials, is completed. This process is expected to take several weeks or months.[32]

On the same day, Hyun-Tak Kim, one of the authors of the 6 author July 22 arXiv-LK-99 paper, provided the New York Times with a new video presumably showing a sample displaying strong signs of diamagnetism.[2] The video appears to show a sample different to the one in the original preprint, suggesting the group's ability to reproduce their samples.

On 4 August 2023, Hyun-Tak Kim informed SBS News that high-quality LK-99 samples may exhibit diamagnetism 5,450 times greater than graphite, while low-quality samples may demonstrate an effect up to 22.7 times stronger. Moreover, he claimed that the diamagnetism of LK-99 is inexplicable unless the substance is a superconductor,[33] a hypothesis also proposed in a theoretical paper on LK-99 by TU Wien and Northwest University.

Authors

Author credit[a 1] 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 Professor[8]†
W&M Professor
Q-Centre (주)퀀텀에너지연구소 CEO R&D Director Yes Yes 'former CTO[8] CTO
Patent (2020)[22] 1 2
Patent Application (2021)[23] 1 2 3
Lee & Kim+ (18 April 2023)[4] 1 2 3 4 5 6 Acknowledged
Lee & Kim+ (22 July 2023.a)[3] 1 2 Acknowledged Acknowledged 3 Acknowledged
Lee & Kim+ (22 July 2023.b)[10] 1 2 3 4 5 Acknowledged 6 Acknowledged
  1. ^ ("1" = first author, "2" = second author, etc.)

Response

Materials scientists and superconductor researchers responded with skepticism.[9][34] The highest-temperature superconductors known at the time of publication had a critical temperature of 250 K (−23 °C; −10 °F) at pressures of over 170 gigapascals (1,680,000 atm; 24,700,000 psi). The highest-temperature superconductors at atmospheric pressure (1 atm) had a critical temperature of at most 150 K (−123 °C; −190 °F).

On 2 August 2023, the The Korean Society of Superconductivity and Cryogenics established a verification committee as a response to the controversy and unverified claims of LK-99, in order to arrive at conclusions over these claims. The verification committee is headed by Kim Chang-Young of Seoul National University and consists of members of the university, Sungkyunkwan University and Pohang University of Science and Technology. Upon formation, the verification committee did not agree that the two 22 July arXiv papers by Lee et al. or the publicly available videos at the time supported the claim of LK-99 being a superconductor.[27][35] The measured changes in the conduction with temperature can be also modeled as a response from a stochastic network of non-uniform semiconducting materials[36][37] as noted by Jorge E. Hirsch.

As of 7 August 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.[9] An alternative explanation for LK-99's stated partial magnetic levitation could be solely from non-superconductive diamagnetism.[27][38]

Public response

The claims of a room-temperature superconductor in the 22 July papers by Lee et al. went viral on social media platforms the following week,[7] including Twitter and Reddit.[39] The viral nature of the claim resulted in posts from users using pseudonyms from Russia and China claiming to have replicated LK-99 on both Twitter and Zhihu.[40] Other claims came from viral videos that described themselves as having replicated samples of LK-99 levitating, some of which were found to be fake.[34] Despite interest from commentators, scientists interviewed by the press remained skeptical.[41][42] Reasons given for skepticism included issues with the Lee et al. July 22 preprint papers, the lack of purity in the sample reported by Lee et al. and the failure of previous claims of room temperature superconductivity to show legitimacy.[27] The Korean Society of Superconductivity and Cryogenics has expressed concern on the social and economic impacts of the LK-99 research, as it has not been verified nor peer-reviewed.[43]

A video from Huazhong University of Science and Technology uploaded on 1 August 2023 by a postdoctoral researcher on the team of Chang Haixin,[27] apparently showed a micrometre-sized sample of LK-99 levitating that went viral on Chinese social media. Gathering millions of views, it became the second most viewed video on Bilibili the next day.[44] On 3 August, it became the most viewed video on Bilibili with 9 million views.[27] A researcher from the Chinese Academy of Sciences refused to comment on the video for the press, dismissing the claim as "ridiculous".[44] Public excitement grew after the video made its way to western social media, with a prediction market briefly putting the chance of successful replication at 60%.[45]

As the topic of LK-99 trended on Twitter for days at the start of August, users began to create memes about "floating rocks" and suggested backing stocks in superconductors.[46] It was concurrently reported in the press that the study had caused a surge in Korean and Chinese technology stocks,[47][48][49] despite warnings from the Korean stock exchange against speculative bets in light of the excitement around LK-99.[43] Several meme coins based on the substance were created as news of LK-99 reached the crypto community.[50]

Replication attempts

As of 7 August 2023, no replication attempts have yet been peer-reviewed. After the July 2023 publication's release, independent groups reported that they had begun attempting to reproduce the synthesis, with initial results expected within weeks.[7] However while positive results can come quickly, negative results are slow, as "falsification needs to verify all possibilities, and it will take a lot of time."[51]

Early replication efforts gained global visibility, with the aid of online replication trackers that catalogued new announcements and status updates.[40] Some researchers released brief teaser images or videos before publishing any results, which received great public attention.[15]

On August 2nd, a team around Sun Yue at Southeast University, claimed to have measured zero resistance in a flake of LK-99 up to a temperature of 110 K (−163 °C; −262 °F).[2][52] Doubts were expressed by experts in the field. Criticism noted that the results demonstrated what looked like a large measurement artifact, did not show the expected dropoff to zero resistance, were quite noisy, and that instruments used were unable to measure resistance below 10 µΩ, which is high for measurements of superconductors.[34][53]

Experimental studies

Results Key:   Success   Partial Success   Partial Failure   Failure

Group[a 1] Country Status Results Publication Notes
Huazhong University of Science and Technology China Preliminary Successful synthesis of LK-99 and diamagnetism of small (< 0.1 mm) flakes of LK-99 at ambient pressure and room temperature. Reportedly making a new batch to measure resistance. arXiv: Hao Wu, et al.[54]

Video posted to bilibili.[55][56]

Press coverage:[15][27][44][40]

Beihang University Preliminary No diamagnetism observed. LK-99 sample had high resistivity not consistent with superconductivity. arXiv: Li Liu, et al.[57]

Press coverage:[46][58]

Southeast University Preliminary Synthesized LK-99, structure confirmed by x-ray diffraction. Resistance of mm-sized sample gradually reduced from 0.1Ω at room temperature to noise level (10-5Ω) at 110 K and below. No observed Meissner effect. arXiv: Qiang Hou, et al.[6]

Video announcement:[52]

Critical responses:[34][53]

Press coverage:[2]

Shanghai University Unpublished LK-99 powder was measured for magnetic susceptibility. Preliminary results observed no diamagnetism. News report: on-site interview by reporter[59]
Qufu Normal University Unpublished Zero resistance not observed in sample. Press coverage:[49]
National Physical Laboratory of India (CSIR-NPLI) India Preliminary Structure confirmed by x-ray diffraction. No diamagnetism observed. Measurements of superconductivity incomplete. arXiv: Kapil Kumar, et al.[11][60][61]

Press coverage:[27][46][40][58]

National Taiwan University Taiwan Unpublished Found diamagnetic properties, but also measured non-zero resistance and no superconductivity. Li-min, et al.

Live stream:[62][63]

Press coverage:[64]

Varda Space Industries & University of Southern California United States Unpublished Presumably successful synthesis of LK-99. Videos showing partial levitation of small samples in response to magnetic field. Videos shared on Twitter:[65][66]

Team headed by Andrew McCalip. Livestreaming on Twitch and posting on Twitter. Samples to be analysed by University of Southern California.[67]

Press coverage:[27][40][39]

Argonne National Laboratory Un­known Not reported Press coverage:[27][68][40]
Sungkyunkwan University South Korea Un­known Not reported Supporting the committee reportedly evaluating the claims about LK-99.[35]

Press coverage:[27]

Korea University Un­known Not reported
Seoul National University Un­known Not reported
  1. ^ For other reported replications in progress, see the talk page.

Theoretical studies

In the initial papers, the theoretical explanations for potential mechanisms of superconductivity in LK-99 were incomplete. Later analyses by other labs have added further simulations and theoretical evaluations of the material's electronic properties from first principles.

Group Country Result Publication notes
Chinese Academy of Sciences (SYNL) China First-principles study of the electronic structure of LK-99 and other variants. Expresses no opinion on room-temp superconductivity, but suggests gold-doped lead apatite may have stronger effects. arXiv: Junwen Lai, et al.[69]

Media mentions:[70]

Lawrence Berkeley National Laboratory United States DFT analysis on a simplified 3D structure explores possible electronic structure that could be favorable for superconductivity, suggests slightly decreased lattice constant. arXiv: Sinéad Griffin[19][b 1]

Analysis:[71][72]

Media mentions:[45][46]

Northwest University and TU Wien China, Austria Similar results from DFT analysis. Conjectures superconductivity might be possible, but only when LK-99 is doped, and that diamagnetism without superconductivity is unlikely. arXiv: Liang Si & Karsten Held[73][b 1]
CU Boulder, National Renewable Energy Laboratory, and King's College United States, United Kingdom Similar results from DFT analysis. Conjectures this class of material (weak interaction of copper‒oxygen, while minimising hybridisation) shows promise for high-Tc superconductivity, regardless of realisation of LK-99. arXiv: Rafal Kurleto, et al.[74][b 1]
Institute of Mathematical Sciences, Chennai and IIT Madras India Theorises a mechanism for superconductivity within LK-99, in which copper chains in LK-99 act as a Mott insulator and interact with surrounding insulating elements. arXiv: G. Baskaran[75]
University of California, Irvine and University of Toronto United States, Canada A minimal tight-binding model is proposed which reproduces the main features of the flat bands in LK-99 and informs a discussion on the symmetry of a putative superconducting order parameter. arXiv: Omid Tavakol & Thomas Scaffidi[76]
Universidad de Chile Chile DFT analysis, finding large electron-phonon coupling in the flat bands. arXiv: J. Cabezas-Escares, et al.[77]
KAIST and Johns Hopkins South Korea, United States Analysis of a novel two-orbital Hubbard model of LK-99, suggesting that initial DFT calculations would not exhibit superconductivity, but certain Cu doping could produce local clusters that do. arXiv: Oh & Zhang A bot will complete this citation soon. Click here to jump the queue arXiv:2308.02469.
  1. ^ a b c The first three density functional theory analyses were published within 24 hours of one another, and have largely overlapping analysis.

See also

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 Chang, Kenneth (3 August 2023). "LK-99 Is the Superconductor of the Summer". The New York Times. Archived from the original on 3 August 2023. Retrieved 3 August 2023.
  3. ^ a b c d e f g h i Lee, Sukbae; Kim, Ji-Hoon; Kwon, Young-Wan (22 July 2023). "The First Room-Temperature Ambient-Pressure Superconductor". arXiv:2307.12008 [cond-mat.supr-con].
  4. ^ a b c d 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.
  5. ^ 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
  6. ^ a b Qiang Hou; Wei Wei; Xin Zhou; Yue Sun; Zhixiang Shi (2 Aug 2023). "Observation of zero resistance above 100∘ K in Pb10−xCux(PO4)6O". arXiv:2308.01192 [cond-mat.supr-con].
  7. ^ 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.
  8. ^ 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.
  9. ^ 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 [HT] Kim says that the second [3-author] paper contains "many defects" and was uploaded to arXiv without his permission. … Once the findings are published in a peer-reviewed journal, … [HT] Kim says … he will support anyone who wants to create and test LK-99
  10. ^ a b c d e f g h i 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 [cond-mat.supr-con].
  11. ^ a b c Kumar, Kapil (31 July 2023). "Synthesis of possible room temperature superconductor LK-99:Pb9Cu(PO4)6O". arXiv:2307.16402 [cond-mat.supr-con].
  12. ^ Kumar, Kapil; Karn, N. K.; Kumar, Yogesh; Awana, V. P. S. (2023). "Absence of superconductivity in LK-99 at ambient conditions". doi:10.48550/arXiv.2308.03544. {{cite journal}}: Cite journal requires |journal= (help)
  13. ^ Fuhrer, Michael S. [@MichaelSFuhrer] (2 August 2023). "You'd think superconductivity would be easy to detect; it comes with zero electrical resistance, so if you measure resistance, and it's zero, you're done. Unfortunately there are many ways to get fooled" (Tweet). Retrieved 2 August 2023 – via Twitter.
  14. ^ Fuhrer, Michael S. [@MichaelSFuhrer] (2 August 2023). "So generally you'll see multiple pieces of evidence for superconductivity in a new report: Meissner effect, AC susceptibility, temperature-dependent critical field and critical current, single-particle tunnelling gap, jump in specific heat at T_c, Josephson tunnelling... etc" (Tweet). Retrieved 2 August 2023 – via Twitter.
  15. ^ a b c Lowe, Derek (1 August 2023). "A Room-Temperature Superconductor? New Developments". Chemical News. In the pipeline (blog). American Association for the Advancement of Science. Archived from the original on 1 August 2023. Retrieved 1 August 2023 – via Science.org.
  16. ^ Kim, Hyun-Tak (14 May 2021). "Room-temperature-superconducting Tc driven by electron correlation". Scientific Reports. 11 (1): 10329. Bibcode:2021NatSR..1110329K. doi:10.1038/s41598-021-88937-7. ISSN 2045-2322. PMC 8121790. PMID 33990629.
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  20. ^ 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.
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Further reading

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