LK-99

The chemical composition of LK-99 is approximately Pb₉Cu(PO₄)₆O, in which— compared to pure lead-apatite (Pb₁₀(PO₄)₆O){{r|sukbae-2023-2|p=5}}— approximately one quarter of Pb(II) ions in position 2 of the apatite structure are replaced by Cu(II) ions.{{r|sukbae-2023|p=9}}

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

Lee et al. provide a method for chemical synthesis of LK-99{{r|sukbae-2023-2|p=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, heated at {{convert|725|C|K F|round=10}} for 24 hours:

: PbO + Pb(SO₄) → Pb₂(SO₄)O.

Second, 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 {{convert|550|C|K F|sigfig=2}} for 48 hours:{{r|sukbae-2023-2|p=3}}

: 3 Cu + P → Cu₃P.

Finally, lanarkite and copper phosphide crystals are ground into a powder, placed in a sealed tube under a vacuum, and heated to {{convert|925|C|K F|sigfig=3}} for between 5‒20 hours:{{r|sukbae-2023-2|p=3}}

:Pb₂(SO₄)O + Cu₃P → Pb_{10-{{math|x}}}Cu_{{math|x}}(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 ({{chem2|Cu2S}}) as well.{{Cite journal |arxiv=2308.03110 |first1=Kaizhen |last1=Guo |first2=Yuan |last2=Li |first3=Shuang |last3=Jia |title=Ferromagnetic half levitation of LK-99-like synthetic samples |journal=Science China Physics, Mechanics & Astronomy |date=2023-08-06|volume=66 |issue=10 |doi=10.1007/s11433-023-2201-9 |bibcode=2023SCPMA..6607411G |s2cid=260680385}} For $x=1$ a balanced reaction might be:

:5 {{chem2|Pb2SO4O + 6 Cu3P → Pb9Cu(PO4)6O + 5 Cu2S + Pb + 7 Cu}}.{{cite journal |arxiv=2308.03544 |last1=Kumar |first1=Kapil |last2=Karn |first2=N. K. |last3=Kumar |first3=Yogesh |last4=Awana |first4=V. P. S. |title=Absence of superconductivity in LK-99 at ambient conditions |journal=ACS Omega |date=2023-08-07|volume=8 |issue=44 |pages=41737–41743 |doi=10.1021/acsomega.3c06096 |pmid=37969980 |pmc=10633996}}

Many syntheses produced fragmentary results in different phases, where some of the resulting fragments were responsive to magnetic fields, and other fragments were not. The first synthesis to produce pure crystals found them to be diamagnetic insulators.{{Cite journal |arxiv=2308.06256 |title=Single crystal synthesis, structure, and magnetism of Pb10− x Cu x (PO4)6O |first1=P. |last1=Puphal |first2=M. Y. P. |last2= Akbar |first3=M. |last3=Hepting |first4=E. |last4=Goering |first5=M. |last5= Isobe |first6=A. A. |last6= Nugroho |first7= B. |last7= Keimer |journal=APL Materials |date= 2023-08-11|volume=11 |issue=10 |doi=10.1063/5.0172755 |bibcode=2023APLM...11j1128P |s2cid=260866146}}

Some small LK-99 samples were reported to show strong diamagnetic properties, including a response confusingly{{Cite arXiv |eprint=2308.11542 |last1=Chen |first1=Yan-Cong |title=Magical or magnetic? Less commonly taught facts about real-world permanent magnets and their diverse interactions with objects |date=2023 |class=physics.pop-ph}} referred to as "partial levitation" over a magnet.{{r|sukbae-2023-2}} This is a sign of regular diamagnetism or ferromagnetism, however it was misinterpreted by some as a sign of superconductivity.

While initial preprints claimed the material was a room-temperature superconductor,{{rp|1}} they did not report observing any definitive properties of superconductivity, such as 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.{{Cite tweet|number=1686644237742526464|user=MichaelSFuhrer|title=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.|first=Michael S.|last=Fuhrer|author-link=Michael Fuhrer |date=2023-08-02|access-date=2023-08-02|language=en}}

Because it is common for a new material to spuriously seem like a potential candidate for high-temperature superconductivity,{{Cite twitter |first=Michael S. |last=Fuhrer |author-link=Michael Fuhrer |user=MichaelSFuhrer |number=1686644235414720512 |access-date=2023-08-02 |title=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 |language=en}} thorough experimental reports normally demonstrate a number of these properties. None of these properties was ever observed by the original experiment or any replications.{{Cite news |last=Lowe |first=Derek |author-link=Derek Lowe (chemist) |date=2023-08-01 |title=A Room-Temperature Superconductor? New Developments |url=https://www.science.org/content/blog-post/room-temperature-superconductor-new-developments |url-status=live |archive-url=https://web.archive.org/web/20230801202928/https://www.science.org/content/blog-post/room-temperature-superconductor-new-developments |archive-date=2023-08-01 |access-date=2023-08-01 |work=In the pipeline |department=Chemical News |publisher=American Association for the Advancement of Science |type=blog |via=Science.org}}

Partial replacement of Pb²⁺ ions with smaller Cu²⁺ ions is said to cause a 0.48% reduction in volume, creating internal stress in the material,{{r|sukbae-2023|p=8}} causing a heterojunction quantum well between the Pb(1) and oxygen within the phosphate ([PO₄]³⁻). Kim Hyun-Tak proposed that this quantum well could be superconducting{{r|sukbae-2023|p=10}}, in a 2021 paper{{Cite journal |last=Kim |first=Hyun-Tak |date=2021-05-14 |title=Room-temperature-superconducting Tc driven by electron correlation |journal=Scientific Reports |language=en |volume=11 |issue=1 |pages=10329 |bibcode=2021NatSR..1110329K |doi=10.1038/s41598-021-88937-7 |issn=2045-2322 |pmc=8121790 |pmid=33990629}} describing a novel and complicated theory combining ideas from a classical theory of metal-insulator transitions,{{Cite journal |last1=Brinkman |first1=W. F. |last2=Rice |first2=T. M. |date=1970-11-15 |title=Application of Gutzwiller's Variational Method to the Metal-Insulator Transition |url=https://link.aps.org/doi/10.1103/PhysRevB.2.4302 |url-status=live |journal=Physical Review B |language=en |volume=2 |issue=10 |pages=4302–4304 |bibcode=1970PhRvB...2.4302B |doi=10.1103/PhysRevB.2.4302 |issn=0556-2805 |archive-url=https://web.archive.org/web/20230802032758/https://journals.aps.org/prb/abstract/10.1103/PhysRevB.2.4302 |archive-date=2 August 2023 |access-date=1 August 2023|url-access=subscription }} the standard Bardeen–Cooper–Schrieffer theory, and the theory of hole superconductivity{{Cite journal |last=Hirsch |first=J. E. |date=1989-01-23 |title=Hole superconductivity |url=https://dx.doi.org/10.1016/0375-9601%2889%2990370-8 |url-status=live |journal=Physics Letters A |language=en |volume=134 |issue=7 |pages=451–455 |bibcode=1989PhLA..134..451H |doi=10.1016/0375-9601(89)90370-8 |issn=0375-9601 |archive-url=https://web.archive.org/web/20140709222756/http://www.sciencedirect.com/science/article/pii/0375960189903708 |archive-date=9 July 2014 |access-date=1 August 2023|url-access=subscription }} 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 might have correlated isolated flat bands, which might contribute to superconductivity.{{Cite arXiv |eprint=2307.16892 |class=cond-mat.supr-con |first=Sinéad M. |last=Griffin |author-link=Sinéad Griffin |title=Origin of correlated isolated flat bands in copper-substituted lead phosphate apatite |date=2023-07-31}} 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.{{Cite journal |arxiv=2308.00676 |first1=Liang |last1=Si |first2=Karsten |last2=Held |title=Electronic structure of the putative room-temperature superconductor $\backslash text\{Pb\}\_9\backslash text\{Cu\}(\backslash text\{PO\}\_4)\_6\backslash text\{O\}$ |journal=Physical Review B |date=2023-08-01|volume=108 |issue=12 |doi=10.1103/PhysRevB.108.L121110 |s2cid=260351297}} In August, a study by Alexandru Georgescu at Indiana University did not find flat bands at Fermi level, concluding that they related to an unfavored high-symmetry structure.

Analyses by industrial and experimental physicists noted experimental and theoretical shortcomings of the published works. Shortcomings included the lack of phase diagrams spanning temperature, stoichiometry,{{Cite web |last=Padavic-Callaghan |first=Karmela |date=26 July 2023 |title=Room-temperature superconductor 'breakthrough' met with scepticism |url=https://www.newscientist.com/article/2384782-room-temperature-superconductor-breakthrough-met-with-scepticism/ |archive-url=https://archive.today/20230726181113/https://www.newscientist.com/article/2384782-room-temperature-superconductor-breakthrough-met-with-scepticism/#selection-689.37-689.118 |archive-date=2023-07-26 |access-date=2023-07-26 |website=New Scientist |language=en-US}} and stress; the lack of pathways for the very high T_c of LK-99 compared to prior heavy fermion superconductors; the absence of flux pinning in any observations; the possibility of stochastic conductive artifacts 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.

=={{anchor|Name}}Compound name==

The name LK-99 comes from the initials of Lee and Kim, and the year they first started working with the material (1999). The pair had worked with Tong-Seek Chair ({{lang|ko|최동식}}) at Korea University in the 1990s.{{r|chosunbiz-20230727}} In 2008, they founded the Quantum Energy Research Centre (퀀텀 에너지연구소; also known as {{nowrap|Q-Centre}}) with other researchers from Korea University.{{r|yonhap-sjho-20230728}} Lee would later become CEO of {{nowrap|Q-Centre}}, and Kim would become director of research and development.

Lee stated that in 2020, an initial paper was submitted to Nature, but was rejected.{{r|chosunbiz-20230727}} 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.{{r|garisto-20230725}}

In 2020, Lee and Kim Ji-Hoon filed a patent application.{{r|patent-2020}} A second patent application (additionally listing Young-Wan Kwon), was filed in 2021, which was published on 3 March 2023.{{r|patent-2021}} A World Intellectual Property Organization (WIPO) patent was also published on 2 March 2023.{{cite web |title=Room-temperature and atmospheric-pressure superconducting ceramic compound and preparation method therefor |url=https://patents.google.com/patent/WO2023027537A1/en |access-date=5 August 2023 |date=2 March 2023 |archive-date=27 July 2023 |archive-url=https://web.archive.org/web/20230727154613/https://patents.google.com/patent/WO2023027537A1/en |url-status=live}} On 4 April 2023, a Korean trademark application for "LK-99" was filed by the {{nowrap|Q-Centre}}.{{r|trademark}}

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.{{r|sukbae-2023b}} 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 {{nowrap|Q-Centre}} CTO, as third author.{{r|sukbae-2023}} 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.{{r|sukbae-2023-2}}{{cite web |first=Will |last=Henshall |publisher=Time |date=2023-08-03 |access-date=2023-08-03 |title=Why Experts Are Skeptical About That Supposed Superconductor Breakthrough |url=https://time.com/6301391/experts-skeptical-about-ambient-superconductor/ |archive-date=3 August 2023 |archive-url=https://web.archive.org/web/20230803193547/https://time.com/6301391/experts-skeptical-about-ambient-superconductor/ |url-status=live}}

• On 23 July, the findings were also submitted by Lee to APL Materials for peer review.{{r|yonhap-sjho-20230728}} 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.{{cite web |date=2023-08-03 |title=Request for a verification sample from the Quantum Energy Research Institute... Receive a response 2 to 4 weeks after the thesis review |url=https://m.yna.co.kr/view/AKR20230803120200017 |access-date=2023-08-03 |website=Yonhap News Agency}}

Publications describing attempted replications began to be published as soon as the following week.

• 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 strong diamagnetism.{{cite journal |arxiv=2307.16402 |first1=Kapil |last1=Kumar |first2=N.K. |last2=Karn |first3=V.P.S. |last3=Awana |title=Synthesis of possible room temperature superconductor LK-99: Pb₉Cu(PO₄)₆O |journal=Superconductor Science and Technology |date=2023-07-31 |volume=36 |issue=10 |pages=10LT02 |doi=10.1088/1361-6668/acf002 |bibcode=2023SuScT..36jLT02K |s2cid=260333984}}

• On 11 Aug 2023, P. Puphal et al., released their preprint synthesizing the first single crystals of Pb₉Cu(PO₄)₆O finally disproving superconductivity in this chemical stoichiometry published later in APL Materials.{{Cite journal |arxiv=2308.06256 |author1=P. Puphal |author2=M. Y. P. Akbar |title=Single crystal synthesis, structure, and magnetism of Pb10− x Cu x (PO4)6O |date=2023-08-11 |author3=M Hepting |author4=E. Goering |author5=M. Isobe |author6=A. A. Nugroho |author7=B. Keimer|journal=APL Materials |volume=11 |issue=10 |doi=10.1063/5.0172755 |bibcode=2023APLM...11j1128P |s2cid=260866146}}

• On 16 August 2023, Nature published an article declaring that LK-99 had been demonstrated to not be a superconductor, but rather an insulator. It cited statements by an condensed matter experimentalist at the University of California, Davis, and several studies previewed in August 2023.

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.

On 28 July 2023, Kwon presented the findings at a symposium held at Korea University.{{r|kwon-20230728}}{{r|seifert-20230728}}{{r|bodin-20230728}} 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.{{r|yonhap-sjho-20230728}} The article also quoted Lee saying that Kwon had left the {{nowrap|Q-Centre}} Research Institute four months previously.{{r|yonhap-sjho-20230728}}

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. The [https://vp.nyt.com/video/2023/08/03/110377_1_03superconductor-vid_wg_1080p.mp4 video] appears to show a sample different to the one in the original preprint. On 4 August 2023, he told 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.{{cite web |url=https://mnews.sbs.co.kr/news/endPage.do?newsId=N1007295801&plink=SEARCH&cooper=SBSNEWSSEARCH |date=2023-08-04 |access-date=2023-08-04 |title=researcher from Q-Centre speaks with SBS News |archive-date=4 August 2023 |archive-url=https://web.archive.org/web/20230804131746/https://news.sbs.co.kr//news/endPage.do?newsId=N1007295801&plink=SEARCH&cooper=SBSNEWSSEARCH |url-status=live}}

Materials scientists and superconductor researchers responded with skepticism.{{r|padavic-c-20230726}}{{cite journal |journal=Nature |first=Dan |last=Garisto |date=2023-08-04 |title=Claimed superconductor LK-99 is an online sensation — but replication efforts fall short |volume=620 |issue=7973 |page=253 |doi=10.1038/d41586-023-02481-0 |pmid=37542137 |bibcode=2023Natur.620..253G |s2cid=260544005 |url=https://www.nature.com/articles/d41586-023-02481-0 |access-date=2023-08-05 |archive-date=5 August 2023 |archive-url=https://web.archive.org/web/20230805012318/https://www.nature.com/articles/d41586-023-02481-0 |url-status=live|url-access=subscription }} The highest-temperature superconductors known at the time of publication had a critical temperature of {{convert|250|K|C F}} at pressures of over {{convert|170.|GPa|atm psi}}. The highest-temperature superconductors at atmospheric pressure (1 atm) had a critical temperature of at most {{Convert|150|K}}.

On 2 August 2023, 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.{{Cite web |last=Kim |first=Jin-Won |editor=Haeyoung Park |title=S.Korean academics to verify truth of room-temperature superconductor |url=https://www.kedglobal.com/tech,-media-telecom/newsView/ked202308020020 |url-status=live |archive-url=https://web.archive.org/web/20230802153949/https://www.kedglobal.com/tech,-media-telecom/newsView/ked202308020020 |archive-date=2 August 2023 |access-date=2023-08-02 |work=The Korea Economic Daily Global Edition |language=en |department=Tech, Media & Telecom}}

{{As of|2023|08|15|post=,}} the measured properties did not suggest 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.{{r|padavic-c-20230726}} A more likely explanation for LK-99's magnetic response is a mix of ferromagnetism and non-superconductive diamagnetism.{{cite web|url=https://www.popularmechanics.com/science/green-tech/a44764458/lk-99-not-a-superconductor/|access-date=2023-08-10|date=2023-08-09|publisher=Popular Mechanics|first=Darren|last=Orf|title=Well, Seems Like LK-99 Isn't a Room Temperature Superconductor After All|archive-date=10 August 2023|archive-url=https://web.archive.org/web/20230810010424/https://www.popularmechanics.com/science/green-tech/a44764458/lk-99-not-a-superconductor/|url-status=live}}{{r|ritchie-20230726}} A number of studies found that copper(I) sulfide contamination common to the synthesis process could closely replicate the observations that inspired the initial preprints.{{Cite journal |arxiv=2308.04353|author1=Shilin Zhu|author2=Wei Wu|author3= Zheng Li|author4=Jianlin Luo|title=First-order transition in LK-99 containing Cu2S |journal=Matter |date=2023-08-08|volume=6 |issue=12 |pages=4401–4407 |doi=10.1016/j.matt.2023.11.001}}

The claims in the 22 July papers by Lee et al. went viral on social media platforms the following week. 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.{{cite web |last1=Ferreira |first1=Becky |last2=Pearson |first2=Jordan |date=1 August 2023 |title=DIY Scientists and Institutions Are Racing to Replicate the Room-Temperature Superconductor |url=https://www.vice.com/en/article/diy-scientists-and-institutions-are-racing-to-replicate-the-room-temperature-superconductor/ |url-status=live |archive-url=https://web.archive.org/web/20230802153947/https://www.vice.com/en/article/5d9yez/diy-scientists-and-institutions-are-racing-to-replicate-the-room-temperature-superconductor |archive-date=2 August 2023 |access-date=2 August 2023 |website=Vice |language=en}} Other viral videos described themselves as having replicated samples of LK-99 "partially levitating", most of which were found to be fake.

Scientists interviewed by the press remained skeptical,{{Cite web |date=2023-07-27 |title=Superconductor breakthrough could represent 'biggest physics discovery of a lifetime' – but scientists urge caution |url=https://www.independent.co.uk/tech/superconductor-breakthrough-electricity-power-paper-b2382711.html |access-date=2023-08-02 |first=Andrew |last=Griffin |website=www.independent.co.uk |publisher=The Independent |archive-date=28 July 2023 |archive-url=https://web.archive.org/web/20230728223136/https://www.independent.co.uk/tech/superconductor-breakthrough-electricity-power-paper-b2382711.html |url-status=live}}{{Cite web |date=2023-07-27 |title=Viral Superconductor Study Claims to 'Open a New Era for Humankind.' Scientists Aren't So Sure. |url=https://www.vice.com/en/article/viral-room-temperature-superconductor-study-lk-99/ |access-date=2023-08-02 |first=Jordan |last=Pearson |website=Vice.com |publisher=Vice News |language=en-US |archive-date=2 August 2023 |archive-url=https://web.archive.org/web/20230802154007/https://www.vice.com/en/article/bvj7pm/viral-room-temperature-superconductor-study-lk-99 |url-status=live}} because of the quality of both the original preprints, the lack of purity in the sample they reported, and the legitimacy of the claim after the failure of previous claims of room temperature superconductivity did not show legitimacy (such as the Ranga Dias affair). The Korean Society of Superconductivity and Cryogenics expressed concern on the social and economic impacts of the preliminary and unverified LK-99 research.{{cite web |publication-place=Taipei Times |place=Bloomberg News |date=2023-08-04 |access-date=2023-08-04 |title=S Korea experts to test superconductor breakthrough claim |url=https://www.taipeitimes.com/News/biz/archives/2023/08/04/2003804195 |archive-date=4 August 2023 |archive-url=https://web.archive.org/web/20230804131756/https://www.taipeitimes.com/News/biz/archives/2023/08/04/2003804195 |url-status=live}}

A video from Huazhong University of Science and Technology uploaded on 1 August 2023 by a postdoctoral researcher on the team of Chang Haixin, apparently showed a micrometre-sized sample of LK-99 partially levitating. This went viral on Chinese social media, becoming the most viewed video on Bilibili by the next day,{{Cite web |last=Peng |first=Dannie |date=2023-08-02 |title=Superconductor breakthrough could represent 'biggest physics discovery of a lifetime' – but scientists urge caution |url=https://www.scmp.com/news/china/science/article/3229778/could-chinese-teams-viral-lk-99-video-offer-clue-superconductor-holy-grail-physicists |url-status=live |archive-url=https://web.archive.org/web/20230802152233/https://www.scmp.com/news/china/science/article/3229778/could-chinese-teams-viral-lk-99-video-offer-clue-superconductor-holy-grail-physicists |archive-date=2 August 2023 |access-date=2023-08-02 |website=www.scmp.com |publisher=South China Morning Post}} and a prediction market briefly put the chance of successful replication at 60%.{{Cite web |date=2023-08-01 |title=LK-99: Excitement rises over possibly revolutionary 'miracle material' – but there is still no good reason to believe it exists |url=https://www.independent.co.uk/tech/superconductor-lk-99-material-room-temperature-ambient-b2385781.html |access-date=2023-08-02 |first=Andrew |last=Griffin |website=www.independent.co.uk |publisher=The Independent |archive-date=2 August 2023 |archive-url=https://web.archive.org/web/20230802071250/https://www.independent.co.uk/tech/superconductor-lk-99-material-room-temperature-ambient-b2385781.html |url-status=live}} A researcher from the Chinese Academy of Sciences refused to comment on the video for the press, dismissing the claim as "ridiculous".

In early August, people began to create memes about "floating rocks",{{Cite web |last=Ryan |first=Jackson |date=2023-08-02 |title=LK-99 Superconductor: Maybe a Breakthrough, Maybe Not So Much |url=https://www.cnet.com/tech/computing/lk-99-superconductor-maybe-a-breakthrough-maybe-not-so-much/ |archive-url=https://web.archive.org/web/20230802181810/https://www.cnet.com/tech/computing/lk-99-superconductor-maybe-a-breakthrough-maybe-not-so-much/ |archive-date=2023-08-02 |access-date=2023-08-02 |website=www.cnet.com |publisher=CNET}} and there was a brief surge in Korean and Chinese technology stocks,{{Cite web |date=2023-08-01 |title=Superconductor LK-99 Breakthrough Buzz Spurs China, Korea Tech Rally |url=https://www.bloomberg.com/news/articles/2023-08-02/superconductor-breakthrough-buzz-spurs-china-korea-tech-rally |access-date=2023-08-02 |website=www.bloomberg.com |publisher=Bloomberg News |archive-date=2023-08-02 |archive-url=https://web.archive.org/web/20230802200014/https://www.bloomberg.com/news/articles/2023-08-02/superconductor-breakthrough-buzz-spurs-china-korea-tech-rally}}{{Cite news |date=2023-08-02 |title=LK-99 and the Desperation for Scientific Discovery |url=https://www.washingtonpost.com/business/energy/2023/08/02/lk-99-and-the-desperation-for-scientific-discovery/74c4f774-317a-11ee-85dd-5c3c97d6acda_story.html |access-date=2023-08-03 |publication-place=Washington Post |place=Bloomberg News |first=Tim |last=Culpan |newspaper=The Washington Post |archive-date=3 August 2023 |archive-url=https://web.archive.org/web/20230803140836/https://www.washingtonpost.com/business/energy/2023/08/02/lk-99-and-the-desperation-for-scientific-discovery/74c4f774-317a-11ee-85dd-5c3c97d6acda_story.html |url-status=live}}{{Cite web |date=2023-08-04 |title=Superconductor claims spark investor frenzy, but scientists are skeptical |url=https://www.reuters.com/technology/superconductor-claims-spark-investor-frenzy-scientists-are-skeptical-2023-08-03/ |first=Stephen |last=Nellis |access-date=2023-08-04 |publisher=Reuters |archive-date=4 August 2023 |archive-url=https://web.archive.org/web/20230804021045/https://www.reuters.com/technology/superconductor-claims-spark-investor-frenzy-scientists-are-skeptical-2023-08-03/ |url-status=live}} despite warnings from the Korean stock exchange against speculative bets in light of the excitement around LK-99, which eventually fell on August 8.{{Cite web |date=2023-08-09 |title=Superconductor Stocks Drop in Korea Amid Doubts on Breakthrough |url=https://www.bloomberg.com/news/articles/2023-08-09/superconductor-stocks-drop-in-korea-amid-doubts-on-breakthrough |first1=Shinhye |last1=Kang |first2=Youkyung |last2=Lee |access-date=2023-08-09 |publisher=Bloomberg News |url-status=live |archive-date=10 August 2023 |archive-url=https://web.archive.org/web/20230810132925/https://www.bloomberg.com/news/articles/2023-08-09/superconductor-stocks-drop-in-korea-amid-doubts-on-breakthrough}} Following the publication of the Nature article on August 16 that proclaimed LK-99 is not a superconductor, South Korean superconductor stocks fell further, as the interest about LK-99 from investors in previous weeks disappeared.{{Cite web|first=Jin-Won|last=Kim|url=https://www.kedglobal.com/tech,-media-telecom/newsView/ked202308170016|publisher=The Korea Economic Daily|date=2023-08-17|access-date=2023-08-18|title=Korea's superconductor stocks plunge on Nature report|archive-date=18 August 2023|archive-url=https://web.archive.org/web/20230818001932/https://www.kedglobal.com/tech,-media-telecom/newsView/ked202308170016|url-status=live}}

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.{{r|garisto-20230727}} Some replication efforts gained global visibility, with the aid of online replication trackers that catalogued new announcements and status updates.

{{As of|2023|08|15|post=,}} no replication attempts had yet been peer-reviewed by a journal. Of the non-peer-reviewed attempts, over 15 notable labs published results that failed to observe any superconductivity, and a few 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 has a known phase transition at {{Convert|377|K}} from a low-temperature phase to a high-temperature superionic phase, with a sharp rise in resistivity and a λ-like-feature in the heat capacity. Furthermore, Cu₂S is diamagnetic.

Only one attempt observed anything that could have been a 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 {{convert|110|K|C F|lk=in}}.{{Cite web |title=Research on LK-99 Superconductor at Southeast University |url=https://targum.video/embed/388e770217a654ba9175b391eedd7802 |url-status=live |archive-url=https://web.archive.org/web/20230802232401/https://targum.video/embed/388e770217a654ba9175b391eedd7802 |archive-date=2 August 2023 |access-date=2023-08-02 |website=targum.video}} Doubts were expressed by experts in the field, as the study saw no dropoff to zero resistance, had large measurement artifacts, and used crude instruments that could not measure resistance below 10 μΩ (too high to distinguish superconductivity from less exotic low-temperature conductivity).{{Cite twitter|number=1686895266329174016|user=condensed_the|title=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|access-date=2023-08-03|language=en}}

Results Key:

{{legend2|#CCFFCC|{{hash}} Success|border=1px solid #AAAAAA}}

{{legend2|#FFB|{{asterisk}} Partial success|border=1px solid #AAAAAA}}

{{legend2|#FE9|{{‡}} Partial failure|border=1px solid #AAAAAA}}

{{legend2|#FFCCCC|{{†}} Failure|border=1px solid #AAAAAA}}

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. An analysis by Georgescu, et al. comprehensively rebutted the claims of the original preprints, and was updated in early 2025 and published in the peer-reviewed Chemistry of Materials.{{Cite journal |last=Georgescu |first=Alexandru B. |date=2025-03-11 |title=Why Charge Added Using Transition Metals to Some Insulators, Including LK-99, Localizes and Does Not Yield a Metal |url=https://pubs.acs.org/doi/full/10.1021/acs.chemmater.4c02817 |journal=Chemistry of Materials |volume=37 |issue=5 |pages=1847–1853 |doi=10.1021/acs.chemmater.4c02817 |issn=0897-4756|arxiv=2308.07295 }}

Selected theoretical studies:

{{reflist|group="b"|refs=

The first three density functional theory analyses were published within 24 hours of one another, and have largely overlapping analysis.

}}

• Bismuth strontium calcium copper oxide: Superconductivity at T_c ≈ {{convert|33|K|C}} to {{convert|104|K|C}}
• Carbonaceous sulfur hydride: Purported superconductivity at T_c ≈ {{convert|288|K|C}} at 267 GPa
• Lanthanum decahydride: Superconductivity at T_c = {{convert|250|K|C}} at 150 GPa
• Unconventional superconductor

{{reflist|refs=

{{cite news |last=Chang |first=Kenneth |date=August 3, 2023 |title=LK-99 Is the Superconductor of the Summer |url=https://www.nytimes.com/2023/08/03/science/lk-99-superconductor-ambient.html |work=The New York Times |access-date=August 3, 2023 |archive-date=August 3, 2023 |archive-url=https://web.archive.org/web/20230803183814/https://www.nytimes.com/2023/08/03/science/lk-99-superconductor-ambient.html |url-status=live |url-access=subscription}}

{{Cite patent|country=KR|number=102404607|title=초전도체를 포함하는 저저항 세라믹화합물의 제조방법 및 그 화합물 [Method of manufacturing ceramic composite with low resistance including superconductors and the composite thereof]|pubdate=2021-05-31|assign1=Quantum Energy Research Institute Co. Ltd.|inventor1-last=Lee|inventor1-first=Sukbae|inventor2-last=Kim|inventor2-first=Ji-Hoon}}

{{cite patent|title=상온, 상압 초전도 세라믹화합물 및 그 제조방법 [Room temperature and normal pressure superconducting ceramic compound, and method for manufacturing same]|country=WO|number=2023027536|assign1=Quantum Energy Research Institute Co. Ltd.|inventor1-last=Lee|inventor1-first=Sukbae|inventor2-last=Kim|inventor2-first=Ji-Hoon|inventor3-last=Kwon|inventor3-first=Young-Wan|status=application|pubdate=2023-03-02}}

{{cite journal |url=http://journal.kci.go.kr/jkcgct/archive/articleView?artiId=ART002955269 |title=Consideration for the development of room-temperature ambient-pressure superconductor (LK-99) |journal=Korean Crystal Growth and Crystal Technology |doi=10.6111/JKCGCT.2023.33.2.061 |date=2023-03-31 |volume=33 |issue=2 |pages=61‒70 |publisher=Korea Association Of Crystal Growth |first1=Sukbae |last1=Lee |first2=Ji-Hoon |last2=Kim |first3=Sungyeon |last3=Im |first4=Soomin |last4=An |first5=Young-Wan |last5=Kwon |first6=Keun Ho |last6=Auh |access-date=2023-07-25 |archive-date=2023-07-25 |archive-url=https://web.archive.org/web/20230725211223/http://journal.kci.go.kr/jkcgct/archive/articleView?artiId=ART002955269 |url-status=live}}

{{cite report |url=http://engdtj.kipris.or.kr/engdtj/grrt1000a.do?method=biblioTMFrame&masterKey=4020230059989&index=0&kindOfReq=A&valid_fg= |title=LK-99 |issue=4020230059989 |date=2023-04-04 |publisher=Korean Intellectual Property Office |work=Korea Intellectual Property Rights Information Service |quote=LK-99; ... Applicant: Quantum Energy Research Centre ({{nowrap|Q-Centre}}); ... Status: Awaiting Examination |access-date=2023-07-25 |archive-date=2023-07-26 |archive-url=https://web.archive.org/web/20230726200823/http://engdtj.kipris.or.kr/engdtj/grrt1000a.do?method=biblioTMFrame&masterKey=4020230059989&index=0&kindOfReq=A&valid_fg= |url-status=live}}

• {{Cite journal |last=Garisto |first=Dan |date=2023-07-25 |title='A very disturbing picture': another retraction imminent for controversial physicist |url=https://www.nature.com/articles/d41586-023-02401-2 |journal=Nature |volume=620 |issue=7972 |pages=14–16 |language=en |doi=10.1038/d41586-023-02401-2 |pmid=37491414 |bibcode=2023Natur.620...14G |s2cid=260162594 |access-date=28 July 2023 |archive-date=27 July 2023 |archive-url=https://web.archive.org/web/20230727204107/https://www.nature.com/articles/d41586-023-02401-2 |url-status=live|url-access=subscription }}

{{cite arXiv |title=The First Room-Temperature Ambient-Pressure Superconductor |first1=Sukbae |last1=Lee |first2=Ji-Hoon |last2=Kim |first3=Young-Wan |last3=Kwon |date=2023-07-22 |class=cond-mat.supr-con |eprint=2307.12008}}

{{cite arXiv |title=Superconductor Pb_10−xCu_x(PO₄)₆O showing levitation at room temperature and atmospheric pressure and mechanism |first1=Sukbae |last1=Lee |first2=Ji-Hoon |last2=Kim |first3=Hyun-Tak |last3=Kim |first4=Sungyeon |last4=Im |first5=SooMin |last5=An |first6=Keun Ho |last6=Auh |eprint=2307.12037 |date=2023-07-22 |class=cond-mat.supr-con}}

• {{cite news |url=https://inews.co.uk/news/science/room-temperature-superconductors-latest-breakthrough-nonsense-2506774 |title=The latest mega-breakthrough on room-temperature superconductors is probably nonsense |first=Stuart |last=Ritchie |author-link=Stuart J. Ritchie |work=i |date=2023-07-26 |access-date=2023-07-27 |archive-date=2023-07-26 |archive-url=https://web.archive.org/web/20230726220126/https://inews.co.uk/news/science/room-temperature-superconductors-latest-breakthrough-nonsense-2506774 |url-status=live |quote=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.}}
• {{cite news |url=https://www.newscientist.com/article/2384782-room-temperature-superconductor-breakthrough-met-with-scepticism/ |title=Room-temperature superconductor 'breakthrough' met with scepticism |first=Karmela |last=Padavic-Callaghan |work=New Scientist |date=2023-07-26 |access-date=2023-07-26 |archive-date=2023-07-26 |archive-url=https://web.archive.org/web/20230726181825/https://www.newscientist.com/article/2384782-room-temperature-superconductor-breakthrough-met-with-scepticism/ |url-status=live |quote=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}}
• {{Cite magazine |url=https://www.scientificamerican.com/article/viral-new-superconductivity-claims-leave-many-scientists-skeptical/ |title=Viral New Superconductivity Claims Leave Many Scientists Skeptical |first=Dan |last=Garisto |date=2023-07-27 |access-date=2023-07-28 |magazine=Scientific American |department=Materials science |language=en |archive-date=27 July 2023 |archive-url=https://web.archive.org/web/20230727210945/https://www.scientificamerican.com/article/viral-new-superconductivity-claims-leave-many-scientists-skeptical/ |url-status=live}}

{{Cite arXiv |eprint=2308.05222v1 |last1=Jain |first1=Prashant K. |title=Phase transition of copper (I) sulfide and its implication for purported superconductivity of LK-99 |date=2023 |class=cond-mat.supr-con}}

• {{cite news |url=https://n.news.naver.com/article/366/0000920152 |script-title=ko:'노벨상감' 상온 초전도체 세계 최초 개발했다는 한국 연구...과학계 '회의론' 넘을까 |trans-title=Korean study into world's first room-temperature superconductor ... can it overcome scientific 'skepticism' ... to win Nobel prize |work=Chosun Biz |author1=이병철 |author2=최정석 |date=2023-07-27 |access-date=2023-07-27 |script-quote=ko: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. |language=ko |archive-date=2023-07-27 |archive-url=https://web.archive.org/web/20230727110149/https://n.news.naver.com/article/366/0000920152 |url-status=live}}
• {{cite conference |title=The World First: Room-Temperature Ambient-Pressure Superconductor |conference=MML 2023: 11th International Symposium on Metallic Multilayers |date=28 July 2023 |location=Korea University, Seoul, Korea |first=Young-Wan |last=Kwon |publisher=The Korean Magnetics Society |conference-url=https://www.mml2023.org/ |type=conference presentation}}
• {{cite twitter |first=Tom S. |last=Seifert |user=TeraTom_S |number=1684808086547238912 |date=2023-07-28 |access-date=2023-07-28 |title=Just listening to an impressive talk of one of the coauthors of the room-temperature superconductor #LK99 at Korea university, Young-Wan Kwon.}}
• {{cite twitter |first=Kenneth |last=Bodin |user=KennethBodin |number=1684831376850157568 |date=2023-07-28 |access-date=2023-07-28 |title=They have now also presented at MML2023. They took questions. Answers not entirely satisfying. Rumour is that {{abbr|MIT|Massachusetts Institute of Technology}} {{abbr|SC|superconductivity}} specialists are flying over to scrutinize experiments. (Photo @JohanaAkerman [Johaa Akerman]) |others=Photograph by Johaa Akerman}}
• {{cite news |url=https://www.yna.co.kr/view/AKR20230728146700017 |language=ko |script-title=ko:'상온 초전도체 구현' 한국 연구에 국내외 논란..."검증 거쳐야" |trans-title=Controversy both domestic and abroad regarding Korean development of room temperature superconductor ... "It has to be verified" |date=2023-07-28 |access-date=2023-07-28 |author=조승한 |editor=강의영 |publisher=Yonhap News Agency |script-quote=ko:... 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. |archive-date=28 July 2023 |archive-url=https://web.archive.org/web/20230728124520/https://www.yna.co.kr/view/AKR20230728146700017 |url-status=live}}
• {{cite journal |url=https://www.science.org/content/article/spectacular-superconductor-claim-making-news-here-s-why-experts-are-doubtful |title=A spectacular superconductor claim is making news. Here's why experts are doubtful |journal=Science |first=Adrian |last=Cho |date=2023-07-27 |access-date=2023-07-29 |doi=10.1126/science.adk0021 |publisher=American Association for the Advancement of Science |quote=Michael Norman, a theorist at Argonne National Laboratory ... says, researchers at Argonne and elsewhere are already trying to replicate the experiment. |archive-date=29 July 2023 |archive-url=https://web.archive.org/web/20230729055410/https://www.science.org/content/article/spectacular-superconductor-claim-making-news-here-s-why-experts-are-doubtful |url-status=live|url-access=subscription }}

}}

{{refbegin}}

• {{cite book |url=https://kupress.com/books/3248/ |script-title=ko:초전도 혁명의 이론적 체계 |trans-title=Theoretical Framework of the Superconducting Revolution |date=1994-05-17 |isbn=89-7641-276-1 |author=최동식 |publisher=고려대학교출판부 |language=ko |access-date=2023-07-27 |archive-date=2023-07-27 |archive-url=https://web.archive.org/web/20230727055743/https://kupress.com/books/3248/ |url-status=live}}
• {{cite journal |url=https://dl.dongascience.com/magazine/view/S199309N024 |journal=Donga Science |date=September 1993 |pages=106‒107 |type=Interview with T.S. Chair |language=ko |title=최동식 |access-date=3 August 2023 |archive-date=20 March 2023 |archive-url=https://web.archive.org/web/20230320130141/https://dl.dongascience.com/magazine/view/S199309N024 |url-status=live}}
• {{cite journal |title=Crystal chemistry of lead oxide phosphates: crystal structures of Pb₄O(PO₄)₂, Pb₈O₅(PO₄)₂ and Pb₁₀(PO₄)₆O |date=2002-10-17|publication-date=2003-05-01 |first1=Sergey V. |last1=Krivovichev |first2=Peter C. |last2=Burns |journal=Zeitschrift für Kristallographie – Crystalline Materials |volume=218 |issue=5 |pages=357–365 |doi=10.1524/zkri.218.5.357.20732 |publisher=Oldenbourg Wissenschaftsverlag |location=Munich |s2cid=101229927 |quote=The compound Pb₁₀(PO₄)₆O has been designated 'oxypyromorphite' ... Pb₁₀(PO₄)₆O crystallizes with an apatite-type structure. The structure contains a single O atom that is not part of a PO₄ tetrahedron; it has a site occupancy factor of 0.25 and is located on the 6₃ axis.}}
• {{cite news |url=https://www.science.org/content/blog-post/breaking-superconductor-news |title=Breaking Superconductor News |first=Derek |last=Lowe |author-link=Derek Lowe (chemist) |work=In the Pipeline |type=blog |date=2023-07-26 |access-date=2023-07-26 |department=Chemical News |via=Science.org |publisher=American Association for the Advancement of Science |archive-date=2023-07-26 |archive-url=https://web.archive.org/web/20230726174644/https://www.science.org/content/blog-post/breaking-superconductor-news |url-status=live}}
• {{cite magazine |url=https://www.popularmechanics.com/science/energy/a44657321/room-temperature-superconductor/ |title=Scientists Claim They Found the Holy Grail of Superconductors |first=Darren |last=Orf |magazine=Popular Mechanics |date=2023-07-27 |access-date=2023-07-28 |department=Energy}}
• {{cite web |last1=Harris |first1=Margaret |title=Have scientists in Korea discovered the first room-temperature, ambient-pressure superconductor? |work=Superconductivity blog |series=Physics World |date=27 July 2023 |url=https://physicsworld.com/a/have-scientists-in-korea-discovered-the-first-room-temperature-ambient-pressure-superconductor/ |access-date=2023-07-29 |publisher=Institute of Physics |archive-date=28 July 2023 |archive-url=https://web.archive.org/web/20230728233445/https://physicsworld.com/a/have-scientists-in-korea-discovered-the-first-room-temperature-ambient-pressure-superconductor/ |url-status=live}}
• {{Cite news |date=2023-07-28 |type=broad overview |script-title=zh:南大教授谈韩国室温超导: 不像超导, 正重复实验—新闻 |trans-title=NU professor talks about room temperature superconductivity found in South Korea: Unlike superconductivity, experiments are being repeated |url=https://news.sciencenet.cn/htmlnews/2023/7/505675.shtm |url-status=live |archive-url=https://web.archive.org/web/20230731054842/https://news.sciencenet.cn//htmlnews/2023/7/505675.shtm |archive-date=31 July 2023 |access-date=31 July 2023 |work=ScienceNet.cn |language=zh |author1=Wu, Yuewei |author2=Sun, Wenya |author3=Li, Ruiyang |quote= }}
• {{cite news|url=https://m.dt.co.kr/contents.html?article_no=2023080802109931650002|author=안경애|language=ko|script-title=ko:"'LK-99 샘플' 미세 결정구조 논문과 같다"...에너지공대 확인|date=2023-08-08|access-date=2023-08-09|work=Digital Times|trans-title=The 'LK-99' sample crystal structure matches published paper — [Korea University] College of Energy Engineering|quote=LK-99 연구에 참여하고 있는 한국에너지공대의 한 연구자는 8일 디지털타임스와의 통화에서 "샘플에 대한 X선 회절구조 분석 결과, 논문에 제시된 것과 샘플의 미세 결정구조가 같다는 사실을 확인했다"고 밝혔다. 이 연구자는 "미세 결정구조를 보면 물질의 물성을 확인하지 못해도 가능성을 추정할 수 있다. LK-99 분석을 위해 X레이로 미세 결정구조를 확인한 결과, 퀀텀에너지연구소 측이 논문에서 밝힌 결정구조와 샘플에서 확인되는 결정구조가 같았다"고 말했다.|archive-date=10 August 2023|archive-url=https://web.archive.org/web/20230810132840/https://m.dt.co.kr/contents.html?article_no=2023080802109931650002|url-status=live}}
• {{cite journal|arxiv=2308.04353|title=First-order transition in LK-99 containing Cu2S|author1=Shilin Zhu|author2=Wei Wu|author3=Zheng Li|author4=Jianlin Luo|journal=Matter |date=2023-08-08|volume=6 |issue=12 |pages=4401–4407 |doi=10.1016/j.matt.2023.11.001}}
• {{cite journal|arxiv=2308.06256|title=Single crystal synthesis, structure, and magnetism of Pb10− x Cu x (PO4)6O|first1=P.|last1=Puphal|first2=M. Y. P.|last2=Akbar|first3=M.|last3=Hepting|first4=E.|last4=Goering|first5=M.|last5=Isobe|first6=A. A.|last6=Nugroho|first7=B.|last7=Keimer|journal=APL Materials |date=2023-08-11|volume=11 |issue=10 |doi=10.1063/5.0172755 |bibcode=2023APLM...11j1128P |s2cid=260866146}}

{{refend}}

• {{Cite video |title=Magnetic Property Test of LK-99 Film |url=https://www.youtube.com/watch?v=EtVjGWpbE7k |date=2023-01-26 |access-date=2023-07-25 |publisher=Quantum Energy Research Centre |type=video |via=Youtube}} This effect is a conductive copper plate induced by a magnetic.
• {{Cite video |first=Hyun-Tak |last=Kim |title=Superconductor Pb_10−xCu_x(PO₄)₆O showing levitation at room temperature and atmospheric pressure and mechanism |date=2023-07-25 |access-date=2023-07-25 |via=ScienceCast |url=https://sciencecast.org/casts/suc384jly50n |type=video}}
• List of replication claims, regularly updated:
• [https://forums.spacebattles.com/threads/claims-of-room-temperature-and-ambient-pressure-superconductor.1106083/ Compilation of Known Replication Attempt Claims]. Guderian2nd, Spacebattles Forums. Retrieved 2 August 2023.
• [https://eirifu.wordpress.com/2023/07/30/lk-99-superconductor-summary/ LK-99#Online Claims]. Eiri Sanada. Retrieved 2 August 2023.

Category:2023 in science

Category:Lead(II) compounds

Category:Phosphates

Category:Science and technology in South Korea

Category:Superconductivity

Category:Crystals in space group 176