Jump to content

LK-99

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by Cyp (talk | contribs) at 16:48, 16 August 2023 ((PO₄)6₀ → (PO₄)₆O). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

LK-99

3D structure
Identifiers
  • 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
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)[1] is a gray–black, polycrystalline compound, identified as a copper-doped lead‒oxyapatite. A team from Korea University led by Lee Sukbae (이석배) and Kim Ji-Hoon (김지훈) began studying this material as a potential superconductor starting in 1999.[2]: 1  In 2023, they published preprints claiming that it acts as a room-temperature superconductor[2]: 8  at temperatures of up to 400 K (127 °C; 260 °F) at ambient pressure.[1][3][2]: 1 

Many different labs attempted to replicate the work, and were able to reach initial results within weeks, as the process of producing the material is relatively straightforward.[4] As of 14 August 2023, the consensus is that it is an insulator in pure form, and not a superconductor at any temperature,[5][6][7][8] but that copper-deficient copper(I) sulfide[9] formed as an impurity in the proposed synthesis can produce resistance drops, lambda transition in heat capacity, and magnetic response in small samples, which mimic transitions in superconductors.[10][11][9][12] [13][14]

While no replications have gone through the peer-review process of a journal, the first attempted replications were reviewed by a materials science lab. A number of replication attempts identified ferromagnetic and diamagnetic causes for partial levitation of small fragments,[15] the one feature of the original paper that was widely replicated.

The initial studies announcing the discovery of LK-99 were uploaded to arXiv, an open-access preprint archive. Lee later claimed the uploaded preprints were incomplete,[16] and coauthor Kim Hyun-Tak (김현탁) stated that one of the papers contained flaws.[17]

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)[18]: 5 — approximately one quarter of Pb(II) ions in position 2 of the apatite structure are replaced by Cu(II) ions.[2]: 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[18]: 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:[18]: 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:[18]: 3 

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

There were a number of problems with the above synthesis from the initial paper. The reaction is not balanced, and others reported the presence of copper(I) sulfide (Cu2S) as well.[19][11] For a balanced reaction might be:

5 Pb2SO4O + 6 Cu3P → Pb9Cu(PO4)6O + 5 Cu2S + Pb + 7 Cu.[20]

Many syntheses produced fragmentary results in different phases, where some of the resulting fragments were responsive to magnetic fields, other fragments were not.[21] The first synthesis to produce pure crystals found them to be diamagnetic insulators.[22]

Physical properties

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

Some LK-99 samples were reported to show strong diamagnetic properties, including partial levitation over a magnet.[18] This was widely interpreted as a sign of superconductivity, although it is more commonly a sign of regular diamagnetism or ferromagnetism.

While the initial preprints claimed the material is a room-temperature superconductor,[18]: 1  they did not claim to have seen any definitive features of superconductivity, including zero resistance, the Meissner effect, 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.[23]

As it is common for a new material to spuriously seem like a potential candidate for high-temperature superconductivity,[13] thorough experimental reports would normally demonstrate a number of these expected properties. As of 15 August 2023, none of these properties have been observed by the original experiment or by attempted replications.[24]

Proposed mechanism for superconductivity

Partial replacement of Pb2+ ions with smaller Cu2+ ions is said to cause a 0.48% reduction in volume, creating internal stress inside the material.[2]: 8  The internal stress is proposed 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 

This proposed mechanism is based on a 2021 paper[25] by Kim Hyun-Tak describing a complicated theory of superconductivity combining ideas from a classical theory of metal-insulator transitions,[26] the standard Bardeen–Cooper–Schrieffer theory of superconductivity, and a controversial theory of hole superconductivity[27] by J.E.Hirsch.

Response

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, and suggesting this might contribute to superconductivity.[28] However while other researchers agreed with the DFT analysis, a number suggested that this was not compatible with superconductivity, and that a structure different from what was described in Lee, et al. would be necessary.[29]

Analyses by industrial and experimental physicists noted experimental and theoretical shortcomings of the published works.[30] Shortcomings included the lack of phase diagrams[27] spanning temperature, stoichiometry[31] and stress; the lack of pathways for the very high Tc of LK-99 compared to prior heavy fermion superconductors; the absence of flux pinning in any observations; the possibility of stochastic conductive artifacts[32] in conductivity measurements; the high resistance and low current capacity of the alleged superconducting state; and the lack of direct transmission electron microscopy (TEM) of the materials.

Compound name

The name LK-99 comes from the initials of discoverers Lee and Kim, and the year of discovery (1999).[1] The pair had worked with Tong-Seek Chair (최동식) at Korea University in the 1990s.[33]

In 2008, they founded the Quantum Energy Research Centre (퀀텀 에너지연구소; also known as Q-Centre) with other researchers from Korea University .[16] Lee would later become CEO of Q-Centre, and Kim would become director of research and development.

Publication history

Lee has stated that in 2020, an initial paper was submitted to Nature, but was rejected.[33] Similarly-presented research on room-temperature superconductors (but a completely 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.[34]

In 2020, Lee and Kim Ji-Hoon filed a patent application.[35] A second patent application (additionally listing Young-Wan Kwon), was filed in 2021, which was published on 3 March 2023.[36] A World Intellectual Property Organization (WIPO) patent was also published on 2 March 2023.[37] On 4 April 2023, a Korean trademark application for "LK-99" was filed by the Q-Centre.[38]

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.[3] 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.[2] The second preprint was submitted only 2 hours later by Kim Hyun-Tak, former principal researcher at the Electronics & Telecommunications Research Institute and professor at the College of William & Mary, listing himself as third author, as well as three new authors.[18][39]

On 23 July, the findings were also submitted by Lee to APL Materials for peer review.[33][16] On 3 August 2023, a newly-formed Korean LK-99 Verification Committee requested a high-quality sample from the original research team. The team responded that they would only provide the sample once the review process of their APL paper was completed, expected to take several weeks or months.[40]

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.[19]

Other discussion by authors

On 26 July 2023, Kim Hyun-Tak stated in an interview with the New Scientist that the first paper submitted by Kwon contained "many defects" and was submitted without his permission.[31][39]

On 28 July 2023, Kwon presented the findings at a symposium held at Korea University.[41][42][43] 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.[16] The article also quoted Lee saying that Kwon had left the Q-Centre Research Institute four months previously.[16]

On the same day, Kim Hyun-Tak provided the New York Times with a new video presumably showing a sample displaying strong signs of diamagnetism.[1] The video appears to show a sample different to the one in the original preprint. On 4 August 2023, he informed SBS News that high-quality LK-99 samples may exhibit diamagnetism over 5,000 times greater than graphite, which he claimed would be inexplicable unless the substance is a superconductor.[44]

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)
HYU Professor Emeritus
KU‒KIST 'former Professor[16]†
W&M Professor
Q-Centre (주)퀀텀에너지연구소 CEO R&D Director Yes Yes 'former CTO[16] CTO
Patent (2020)[35] 1 2
Patent Application (2021)[36] 1 2 3
Lee & Kim+ (18 April 2023)[3] 1 2 3 4 5 6
Lee & Kim+ (22 July 2023.a)[2] 1 2 Acknowledged Acknowledged 3 Acknowledged
Lee & Kim+ (22 July 2023.b)[18] 1 2 3 4 5 Acknowledged 6
  1. ^ ("1" = first author, "2" = second author, etc.)

Response

Materials scientists and superconductor researchers responded with skepticism.[17][45] 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.[39][46]

As of 10 August 2023, the measured properties do not prove that LK-99 is a superconductor. The published material does not explain how the LK-99's magnetisation can change, demonstrate its specific heat capacity, or demonstrate it crossing its transition temperature.[17] An alternative explanation for LK-99's stated partial magnetic levitation could be from a mix of ferromagnetism and non-superconductive diamagnetism.[39][15][47] A number of studies found that copper(I) sulfide contamination common to the synthesis process could explain the observations that inspired the initial preprints.[9][10]

Public response

The claims in the 22 July papers by Lee et al. went viral on social media platforms the following week.[4][48] 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.[49] Other viral videos described themselves as having replicated samples of LK-99 levitating, most of which were found to be fake.[45]

Scientists interviewed by the press remained skeptical,[50][51] of both the original preprints, the lack of purity in the sample they reported, and the failure of previous claims of room temperature superconductivity to show legitimacy.[39] The Korean Society of Superconductivity and Cryogenics expressed concern on the social and economic impacts of the preliminary and unverified LK-99 research.[52]

A video from Huazhong University of Science and Technology uploaded on 1 August 2023 by a postdoctoral researcher on the team of Chang Haixin,[39] apparently showed a micrometre-sized sample of LK-99 levitating. This went viral on Chinese social media, becoming the most viewed video on Bilibili by the next day,[53][39] and a prediction market briefly put the chance of successful replication at 60%.[54] A researcher from the Chinese Academy of Sciences refused to comment on the video for the press, dismissing the claim as "ridiculous".[53]

In early August, people began to create memes about "floating rocks",[55] meme coins based on the substance were created,[56] and there was a brief surge in Korean and Chinese technology stocks,[57][58][59] despite warnings from the Korean stock exchange against speculative bets in light of the excitement around LK-99,[52] which fell again by On August 8.[60]

Replication attempts

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.[4] However while positive results could potentially come quickly, negative results are slow, as "falsification needs to verify all possibilities, and it will take a lot of time".[61]

As of 15 August 2023, no replication attempts had yet been peer-reviewed by a journal. Of the non-peer-reviewed attempts, over 15 notable labs have published results that failed to observe any superconductivity, and a few have observed magnetic response in small fragments that could be explained by normal diamagnetism or ferromagnetism. Some demonstrated and replicated alternate causes of the observations in the original papers: Copper-deficient copper (I) sulfide[9] has a known phase transition at 377 K (104 °C; 219 °F) from a low-temperature phase to a high-temperature superionic phase, with an sharp rise in resistivity[10][9] and a λ-like-feature in the heat capacity[9]. Furthermore, Cu2S is diamagnetic.

Only one attempt observed any sign of superconductivity: Southeast University claimed to measure very low resistance in a flake of LK-99, in one of four synthesis attempts, below a temperature of 110 K (−163 °C; −262 °F).[1][62] Doubts were expressed by experts in the field, as they saw no dropoff to zero resistance, and used crude instruments that could not measure resistance below 10 μΩ ( too high to distinguish superconductivity from less exotic low-temperature conductivity), and had large measurement artifacts.[45][63]

Some replication efforts gained global visibility, with the aid of online replication trackers that catalogued new announcements and status updates.[49][24]

Experimental studies

Results Key:   Success   Partial success   Partial failure   Failure

Group Country/region Status Results Publication notes
Huazhong University of Science and Technology  China Preliminary Measured diamagnetism of small micrometre sized flakes. Observed resistance cannot drop to zero. Suggests purity of sample is important. arXiv: Hao Wu, et al.[30][14]

Video posted to bilibili.[32][64]

Press coverage:[24][39][53][49]

Beihang University Preliminary No diamagnetism observed. High resistivity not consistent with superconductivity. arXiv: Li Liu, et al.[65]

Press coverage:[55][66]

Southeast University Preliminary 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.[67][68]

Video announcement:[62]

Critical responses:[45][63]

Press coverage:[1]

Peking University Preliminary No Meissner effect nor zero resistivity observed in reproduced sample. arXiv: Kaizhen Guo, et al.[69]
Chinese Academy of Sciences (Condensed Matter) Preliminary No superconductivity observed. Proposed explanation of resistivity reduction by phase change of Cu2S impurities, which others have predicted to be present when partial levitation is observed. arXiv: Shilin Zhu, et al.[10]
Shanghai University Unpublished Synthesized LK-99 powder, saw no diamagnetism. News report: on-site interview by reporter[70]
Qufu Normal University Unpublished LK-99 sample had non-zero resistance. Press coverage:[59]
DIPC, Princeton, Max Planck Institut  Spain,  USA,  Germany Preliminary Synthesized LK-99, found to be multiphase material. Performed single-crystal analysis with X-ray diffraction, finding no superconductivity. Tested 4 different Cu dopings, finding samples to be magnetic rather than superconducting. arXiv: Jiang, et al.[71]
University of Manchester  United Kingdom Preliminary Synthesized and characterized samples of LK-99, no superconductivity detected. arXiv: Ivan Timokhin et al.[72]
National Physical Laboratory of India (CSIR-NPLI)  India Preliminary Initial attempt: Structure confirmed by x-ray diffraction. No diamagnetism observed, no features of superconductivity.

Later attempt recorded sample standing vertically locked in magnetic field.

Video by V.P.S Awana:[73]

arXiv: Kapil Kumar, et al.[19][74][75]

Press coverage:[39][55][49][66]

Lebedev Physics Institute  Russia Unpublished Structure confirmed with X-ray diffraction. No diamagnetism was observed. High resistance observed with 4-point probes method. Resistance increases when temperature decreases. Statement by Lebedev Physics Institute:[76]

Press coverage:[77][78]

National Taiwan University  Taiwan Unpublished Diamagnetism observed. Non-zero resistance, no superconductivity. Li-min, et al.

Live stream:[79][80]

Press coverage:[5]

Varda Space Industries & University of Southern California  United States Unpublished Synthesis of LK-99. Only a few fragments responded to magnetic field.

Analysis showed impurities of Iron and Cu2S, suggested this explained observed phenomenon rather than superconductivity.

Videos shared on Twitter:[81][82]

Team headed by Andrew McCalip. Livestreaming on Twitch and posting on Twitter. Samples analysed by University of Southern California.[83][12]

Press coverage:[39][49][48]

University of Colorado Boulder Unpublished Samples have failed tests for superconductivity. Daniel Dessau, et al.

Press Coverage:[6]

Argonne National Laboratory Un­known Not reported Press coverage:[39][84][49]
Sungkyunkwan University  South Korea Un­known Not reported Supporting the committee reportedly evaluating the claims about LK-99.[46]

Press coverage:[39]

Korea University Un­known Not reported
Seoul National University Un­known Not reported

Theoretical studies

In the initial papers, the theoretical explanations for potential mechanisms of superconductivity in LK-99 were incomplete. Later analyses by other labs added 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. arXiv: Junwen Lai, et al.[85]

Media mentions:[86]

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.

Similar work published the next day by Si & Held[29] and Kurleto, et al.[87]

arXiv: Sinéad Griffin[28][b 1]

Analysis:[88][89]

Media mentions:[54][55]

Universidad de Chile  Chile DFT analysis, finding large electron-phonon coupling in the flat bands. arXiv: J. Cabezas-Escares, et al.[90]
CIEMAT  Spain,  Armenia Concludes the original synthesis for LK-99 likely produces a heterogenous material, making it hard for others to reproduce the same results arXiv: P. Abramian, et al.[21]
Northwest University (China) and TU Wien  China,  Austria Concludes Pb9Cu(PO4)6O, without further doping, it is an insulator. Analyzes possible effects of doping. arXiv: Liang Si & Karsten Held[29][b 1]
  1. ^ a b The first three density functional theory analyses were published within 24 hours of one another, and have largely overlapping analysis.

See also

References

  1. ^ 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.
  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 [cond-mat.supr-con].
  3. ^ a b c 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. ^ 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.
  5. ^ a b Huang, Tzu-ti (6 August 2023). "South Korea's superconductor claim not replicated in Taiwan experiment | Taiwan News | 2023-08-06 10:06:00". Taiwan News. Archived from the original on 7 August 2023. Retrieved 7 August 2023.
  6. ^ a b Johnson, Carolyn Y. (9 August 2023). "A superconductor claim blew up online. Science has punctured it". The Washington Post. Archived from the original on 9 August 2023. Retrieved 9 August 2023.
  7. ^ Robinson, Dan. "LK-99 slammed as 'not a superconductor at all'". www.theregister.com. Archived from the original on 10 August 2023. Retrieved 10 August 2023.
  8. ^ Padavic-Callaghan, Karmela. "LK-99: Mounting evidence suggests material is not a superconductor". New Scientist. Archived from the original on 9 August 2023. Retrieved 10 August 2023.
  9. ^ a b c d e f Jain, Prashant K. (2023). "Phase transition of copper (I) sulfide and its implication for purported superconductivity of LK-99". arXiv:2308.05222v1 [cond-mat.supr-con].
  10. ^ a b c d Shilin Zhu; Wei Wu; Zheng Li; Jianlin Luo (8 August 2023). "First order transition in Pb10−xCux(PO4)6O (0.9<x<1.1) containing Cu2S". arXiv:2308.04353 [cond-mat.supr-con].
  11. ^ a b Guo, Kaizhen; Li, Yuan; Jia, Shuang (6 August 2023). "Ferromagnetic half levitation of LK-99-like synthetic samples". arXiv:2308.03110 [cond-mat.supr-con].
  12. ^ a b @andrewmccalip (10 August 2023). "Meissner Effect or Bust: Day 12" (Tweet) – via Twitter.
  13. ^ a b 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. ^ a b Hao Wu; Li Yang; Jie Yu; Gaojie Zhang; Bichen Xiao; Haixin Chang (9 August 2023). "Observation of abnormal resistance-temperature behavior along with diamagnetic transition in Pb10−xCux(PO4)6O-based composite". arXiv:2308.05001 [cond-mat.supr-con].
  15. ^ a b Orf, Darren (9 August 2023). "Well, Seems Like LK-99 Isn't a Room Temperature Superconductor After All". Popular Mechanics. Archived from the original on 10 August 2023. Retrieved 10 August 2023.
  16. ^ a b c d e f g 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.
  17. ^ 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
  18. ^ 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 [cond-mat.supr-con].
  19. ^ a b c Kumar, Kapil; Karn, N.K.; Awana, V.P.S. (31 July 2023). "Synthesis of possible room temperature superconductor LK-99: Pb9Cu(PO4)6O". Superconductor Science and Technology. arXiv:2307.16402. doi:10.1088/1361-6668/acf002.
  20. ^ Kumar, Kapil; Karn, N. K.; Kumar, Yogesh; Awana, V. P. S. (7 August 2023). "Absence of superconductivity in LK-99 at ambient conditions". arXiv:2308.03544 [cond-mat.supr-con].
  21. ^ a b Abramian, P.; Kuzanyan, A.; Nikoghosyan, V.; Teknowijoyo, S.; Gulian, A. (2023). "Some remarks on possible superconductivity of composition Pb9CuP6O25". arXiv:2308.01723 [cond-mat.supr-con].
  22. ^ Puphal, P.; Akbar, M. Y. P.; Hepting, M.; Goering, E.; Isobe, M.; Nugroho, A. A.; Keimer, B. (11 August 2023). "Single crystal synthesis, structure, and magnetism of Pb10−xCux(PO4)6O". arXiv:2308.06256 [cond-mat.supr-con].
  23. ^ 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.
  24. ^ 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.
  25. ^ 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.
  26. ^ Brinkman, W. F.; Rice, T. M. (15 November 1970). "Application of Gutzwiller's Variational Method to the Metal-Insulator Transition". Physical Review B. 2 (10): 4302–4304. Bibcode:1970PhRvB...2.4302B. doi:10.1103/PhysRevB.2.4302. ISSN 0556-2805. Archived from the original on 2 August 2023. Retrieved 1 August 2023.
  27. ^ a b Hirsch, J. E. (23 January 1989). "Hole superconductivity". Physics Letters A. 134 (7): 451–455. Bibcode:1989PhLA..134..451H. doi:10.1016/0375-9601(89)90370-8. ISSN 0375-9601. Archived from the original on 9 July 2014. Retrieved 1 August 2023.
  28. ^ a b Griffin, Sinéad M. (31 July 2023). "Origin of correlated isolated flat bands in copper-substituted lead phosphate apatite". arXiv:2307.16892 [cond-mat.supr-con].
  29. ^ a b c Si, Liang; Held, Karsten (1 August 2023). "Electronic structure of the putative room-temperature superconductor Pb9Cu(PO4)6O". arXiv:2308.00676 [cond-mat.supr-con].
  30. ^ a b Hao Wu; Li Yang; Bichen Xiao; Haixin Chang (3 August 2023). "Successful growth and room temperature ambient-pressure magnetic levitation of LK-99". arXiv:2308.01516 [cond-mat.supr-con].
  31. ^ a b 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.
  32. ^ a b 关山口男子技师. 补充视频_哔哩哔哩_bilibili. www.bilibili.com (in Simplified Chinese). Archived from the original on 1 August 2023. Retrieved 1 August 2023.
  33. ^ 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.
  34. ^ Garisto, Dan (25 July 2023). "'A very disturbing picture': another retraction imminent for controversial physicist". Nature. 620 (7972): 14–16. doi:10.1038/d41586-023-02401-2. PMID 37491414. S2CID 260162594. Archived from the original on 27 July 2023. Retrieved 28 July 2023.
  35. ^ a b KR20210062550A, 이석배 & 김지훈, "Method of manufacturing ceramic composite with low resistance including superconductors and the composite thereof", issued 2021-05-31  Archived 3 August 2023 at the Wayback Machine
  36. ^ 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
  37. ^ "Room-temperature and atmospheric-pressure superconducting ceramic compound and preparation method therefor". 2 March 2023. Archived from the original on 27 July 2023. Retrieved 5 August 2023.
  38. ^ 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
  39. ^ a b c d e f g h i j k l Henshall, Will (3 August 2023). "Why Experts Are Skeptical About That Supposed Superconductor Breakthrough". Time. Archived from the original on 3 August 2023. Retrieved 3 August 2023.
  40. ^ "Request for a verification sample from the Quantum Energy Research Institute... Receive a response 2 to 4 weeks after the thesis review". Yonhap News Agency. 3 August 2023. Retrieved 3 August 2023.
  41. ^ 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.
  42. ^ 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" (Tweet). Retrieved 28 July 2023 – via Twitter.
  43. ^ 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.
  44. ^ "researcher from Q-Centre speaks with SBS News". 4 August 2023. Archived from the original on 4 August 2023. Retrieved 4 August 2023.
  45. ^ a b c d Garisto, Dan (4 August 2023). "Claimed superconductor LK-99 is an online sensation — but replication efforts fall short". Nature. 620 (7973): 253. doi:10.1038/d41586-023-02481-0. PMID 37542137. S2CID 260544005. Archived from the original on 5 August 2023. Retrieved 5 August 2023.
  46. ^ a b Kim, Jin-Won. Haeyoung Park (ed.). "S.Korean academics to verify truth of room-temperature superconductor". Tech, Media & Telecom. The Korea Economic Daily Global Edition. Archived from the original on 2 August 2023. Retrieved 2 August 2023.
  47. ^ 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.
  48. ^ a b Barber, Gregory (2 August 2023). "Inside the DIY Race to Replicate LK-99". Wired. Archived from the original on 2 August 2023. Retrieved 2 August 2023.
  49. ^ a b c d e f Ferreira, Becky; Pearson, Jordan (1 August 2023). "DIY Scientists and Institutions Are Racing to Replicate the Room-Temperature Superconductor". Vice. Archived from the original on 2 August 2023. Retrieved 2 August 2023.
  50. ^ Griffin, Andrew (27 July 2023). "Superconductor breakthrough could represent 'biggest physics discovery of a lifetime' – but scientists urge caution". www.independent.co.uk. The Independent. Archived from the original on 28 July 2023. Retrieved 2 August 2023.
  51. ^ Pearson, Jordan (27 July 2023). "Viral Superconductor Study Claims to 'Open a New Era for Humankind.' Scientists Aren't So Sure". www.vice.com. Vice News. Archived from the original on 2 August 2023. Retrieved 2 August 2023.
  52. ^ a b Written at Bloomberg News. "S Korea experts to test superconductor breakthrough claim". Taipei Times. 4 August 2023. Archived from the original on 4 August 2023. Retrieved 4 August 2023.
  53. ^ a b c Peng, Dannie (2 August 2023). "Superconductor breakthrough could represent 'biggest physics discovery of a lifetime' – but scientists urge caution". www.scmp.com. South China Morning Post. Archived from the original on 2 August 2023. Retrieved 2 August 2023.
  54. ^ a b Griffin, Andrew (1 August 2023). "LK-99: Excitement rises over possibly revolutionary 'miracle material' – but there is still no good reason to believe it exists". www.independent.co.uk. The Independent. Archived from the original on 2 August 2023. Retrieved 2 August 2023.
  55. ^ a b c d Ryan, Jackson (2 August 2023). "LK-99 Superconductor: Maybe a Breakthrough, Maybe Not So Much". www.cnet.com. CNET. Archived from the original on 2 August 2023. Retrieved 2 August 2023.
  56. ^ Sun, Zhiyuan (4 August 2023). "Korean superconductor LK-99 joins memecoin craze". Cointelegraph. Archived from the original on 6 August 2023. Retrieved 6 August 2023.
  57. ^ "Superconductor LK-99 Breakthrough Buzz Spurs China, Korea Tech Rally". www.bloomberg.com. Bloomberg News. 1 August 2023. Archived from the original on 2 August 2023. Retrieved 2 August 2023.
  58. ^ Culpan, Tim (2 August 2023). Written at Bloomberg News. "LK-99 and the Desperation for Scientific Discovery". The Washington Post. Washington Post. Archived from the original on 3 August 2023. Retrieved 3 August 2023.
  59. ^ a b Nellis, Stephen (4 August 2023). "Superconductor claims spark investor frenzy, but scientists are skeptical". Reuters. Archived from the original on 4 August 2023. Retrieved 4 August 2023.
  60. ^ Kang, Shinhye; Lee, Youkyung (9 August 2023). "Superconductor Stocks Drop in Korea Amid Doubts on Breakthrough". Bloomberg News. Archived from the original on 10 August 2023. Retrieved 9 August 2023.
  61. ^ 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). Archived from the original on 31 July 2023. Retrieved 31 July 2023.
  62. ^ a b "Research on LK-99 Superconductor at Southeast University". targum.video. Archived from the original on 2 August 2023. Retrieved 2 August 2023.
  63. ^ a b @condensed_the (3 August 2023). "Southeast may have drawn their figure misleadingly. On a linear scale, there seems to be no transition, very disappointing and not a good sign since the artifact also looms large" (Tweet). Retrieved 3 August 2023 – via Twitter.
  64. ^ 关山口男子技师. "LK-99验证_哔哩哔哩_bilibili". www.bilibili.com (in Simplified Chinese). Archived from the original on 1 August 2023. Retrieved 1 August 2023.
  65. ^ Li Liu; Ziang Meng; Xiaoning Wang; Hongyu Chen; Zhiyuan Duan; Xiaorong Zhou; Han Yan; Peixin Qin; Zhiqi Liu (31 July 2023). "Semiconducting transport in Pb10-xCux(PO4)6O sintered from Pb2SO5 and Cu3P". arXiv:2307.16802 [cond-mat.supr-con].
  66. ^ a b Tran, Tony Ho (1 August 2023). "Sorry, But the New LK-99 Superconductor Breakthrough Might Be Total BS". www.thedailybeast.com. The Daily Beast. Archived from the original on 1 August 2023. Retrieved 2 August 2023.
  67. ^ Hou, Qiang; Wei, Wei; Zhou, Xin; Sun, Yue; Shi, Zhixiang (2 August 2023). "Observation of zero resistance above 100∘ K in Pb10−xCux(PO4)6O". arXiv:2308.01192 [cond-mat.supr-con].
  68. ^ Hou, Qiang; Wei, Wei; Zhou, Xin; Wang, Xinyue; Sun, Yue; Shi, Zhixiang (2 August 2023). "Current percolation model for the special resistivity behavior observed in Cu-doped Apatite". arXiv:2308.05778 [cond-mat.supr-con].
  69. ^ Kaizhen Guo; Yuan Li; Shuang Kia (6 August 2023). "Ferromagnetic half levitation of LK-99-like synthetic samples". arXiv:2308.03110 [cond-mat.supr-con].
  70. ^ "上大实验最新结果：LK-99晶体未出现抗磁性[The latest results of the Shanghai University experiment: LK-99 crystal does not appear diamagnetism]". www.kankanews.com(Simplified Chinese). Archived from the original on 3 August 2023. Retrieved 3 August 2023.
  71. ^ Jiang (8 August 2023). "Pb9Cu(PO4)6(OH)2: Phonon bands, Localized Flat Band Magnetism, Models, and Chemical Analysis". arXiv submission. Archived from the original on 10 August 2023. Retrieved 9 August 2023.
  72. ^ Timokhin, Ivan; Chen, Chuhongxu; Yang, Qian; Mishchenko, Artem (7 August 2023). "Synthesis and characterisation of LK-99". arXiv:2308.03823 [cond-mat.supr-con].
  73. ^ V.P.S Awana (10 August 2023). "LK-99 VIDEO". Facebook. Archived from the original on 10 August 2023. Retrieved 10 August 2023.
  74. ^ "People@CSIR-NPL – NPL". Archived from the original on 8 June 2023. Retrieved 31 July 2023.
  75. ^ "Dr. V.P.S. Awana, PhD - Editorial Board - Superconductivity - Journal - Elsevier". www.journals.elsevier.com. Archived from the original on 3 August 2023. Retrieved 31 July 2023.
  76. ^ "Ученые из Кореи утверждают, что создали сверхпроводник, работающий при комнатной температуре и атмосферном давлении: комментарии ФИАН". www.lebedev.ru. 27 July 2023. Archived from the original on 10 August 2023. Retrieved 9 August 2023.
  77. ^ Zaitsev, Vasilii (8 August 2023). "Российские физики проверили «революционный» корейский сверхпроводник. Он оказался изолятором". Gazeta.ru. Archived from the original on 8 August 2023. Retrieved 9 August 2023.
  78. ^ Haritonov, Konstantin (8 August 2023). "Российские ученые опровергли работоспособность открытого в Корее сверхпроводника". Gazeta.ru. Archived from the original on 10 August 2023. Retrieved 9 August 2023.
  79. ^ "🔴直播中 台大實驗室 LK-99 煉丹中 週六 16:30 開箱＋測量 直播馬拉松 02 implementation and measurement of superconductor LK-99". YouTube. Archived from the original on 5 August 2023. Retrieved 7 August 2023.
  80. ^ PanSci Taiwan. "🔴 LK-99 性質驗證！室溫超導是真的嗎？@台大實驗室 直播馬拉松 03 measurement of room-temperature superconductor LK-99 at NTU". YouTube. Archived from the original on 6 August 2023. Retrieved 7 August 2023.
  81. ^ @andrewmccalip (4 August 2023). "Meissner effect or bust: Day 8.5" (Tweet). Retrieved 4 August 2023 – via Twitter.
  82. ^ @andrewmccalip (6 August 2023). "[untitled]" (Tweet). Retrieved 6 August 2023 – via Twitter.
  83. ^ @andrewmccalip (31 July 2023). "Meissner effect or bust: Day 4" (Tweet). Retrieved 1 August 2023 – via Twitter.
  84. ^ Cho, Adrian (27 July 2023). "A spectacular superconductor claim is making news. Here's why experts are doubtful". Science. American Association for the Advancement of Science. doi:10.1126/science.adk0021. Archived from the original on 29 July 2023. Retrieved 29 July 2023. Michael Norman, a theorist at Argonne National Laboratory ... says, researchers at Argonne and elsewhere are already trying to replicate the experiment.
  85. ^ Lai, Junwen; Jiangxu, Li; Peitao, Liu; Yan, Sun; Xing-Qiu, Chen (29 July 2023). "First-principles study on the electronic structure of Pb10−xCux(PO4)6O (x = 0, 1)". Journal of Materials Science & Technology. arXiv:2307.16040. doi:10.1016/j.jmst.2023.08.001.
  86. ^ "Breakthrough in Superconductivity: Huazhong University Scientists Report First Successful Replication of LK-99". Beijing Times. 1 August 2023. Archived from the original on 2 August 2023. Retrieved 2 August 2023.
  87. ^ Kurleto, Rafal; Lany, Stephan; Pashov, Dimitar; Acharya, Swagata; van Schilfgaarde, Mark; Dessau, Daniel S. (1 August 2023). "Pb-apatite framework as a generator of novel flat-band CuO based physics, including possible room temperature superconductivity". arXiv:2308.00698 [cond-mat.supr-con].
  88. ^ Sinéad Griffin [@sineatrix] (2 August 2023). "a monster thread on what my paper says, the approximations and the caveats" (Tweet). Retrieved 3 August 2023 – via Twitter.
  89. ^ Condensed Matter Theory Center, UMD [@condensed_the] (1 August 2023). "For such flat band systems, packaged LDA type calculations are of limited utility, but knowing the LDA band structure is again a small, but necessary, step in understanding the physics. Flat bands DO NOT imply SC, flat bands often lead to magnetic instabilities" (Tweet). Retrieved 2 August 2023 – via Twitter.
  90. ^ Cabezas-Escares, J (2023). "Theoretical insight on the LK-99 material". arXiv:2308.01135 [cond-mat.supr-con].

Further reading

Retrieved from "https://en.wikipedia.org/w/index.php?title=LK-99&oldid=1170696835"