View source for LK-99

{{Short description|Proposed superconducting material}}
<!--{{Chronological}} the article does appear to use Chronological ordering-->
{{Use dmy dates|date=July 2023}}
{{Chembox
| ImageFile      = LK-99 pellet.png
| ImageSize      = 200px
| ImageFile1     = File:LK-99_3D_Structure.png
| ImageCaption1  = 3D structure
| Section1       = {{Chembox Identifiers
| StdInChI=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
| StdInChIKey=KZSIWLDFTIMUEG-UHFFFAOYSA-A
| SMILES=[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]
| Jmol=none
}}
| Section2       = {{Chembox Properties
| Pb=9|Cu=1|P=6|O=25
| Appearance = Purple crystal when pure<ref name="nature 2023Aug16" />
| Density = ≈6.699 g/cm<sup>3</sup>
 }}
| Section3       = {{Chembox Structure
| CrystalStruct = hexagonal
| SpaceGroup = ''P''6<sub>3</sub>/''m'', No. 176
| PointGroup =
| LattConst_a = 9.843 Å
| LattConst_c = 7.428 Å
| UnitCellVolume = 623.2 Å<sup>3</sup>
| UnitCellFormulas = 1
 }}
| Section8       = {{Chembox Related
| OtherCompounds = [[Oxypyromorphite]] ([[lead apatite]])
 }}
}}
'''LK-99''' (from the '''Lee-Kim 1999''' research),<ref name="NYTimesLK99Summer" /> also called '''PCPOSOS''',<ref>[https://meetings.aps.org/Meeting/MAR24/Session/A16.2 Bulletin of the American Physical Society], March 2024 meeting notice</ref> is a gray–black, [[polycrystalline]] compound, identified as a [[copper]]-[[Doping (semiconductor)|doped]] [[Lead apatite|lead‒oxyapatite]]. A team from [[Korea University]] led by Lee Sukbae ({{lang|ko|이석배}}) and Kim Ji-Hoon ({{lang|ko|김지훈}}) began studying this material as a potential [[superconductor]] starting in 1999.{{r|sukbae-2023|p=1}} In July 2023, they published [[preprints]] claiming that it acts as a [[room-temperature superconductor]]{{r|sukbae-2023|p=8}} at temperatures of up to {{convert|400|K|C F|lk=in}} at ambient pressure.<ref name="NYTimesLK99Summer" />{{r|sukbae-2023b}}{{r|sukbae-2023|p=1}}

Many different researchers have attempted to [[Reproducibility|replicate]] the work, and were able to reach initial results within weeks, as the process of producing the material is relatively straightforward.{{r|garisto-20230727}} By mid-August 2023, the consensus<ref name="nature 2023Aug16">{{cite journal |last1=Garisto |first1=Dan |title=LK-99 isn't a superconductor — how science sleuths solved the mystery: Replications pieced together the puzzle of why the material displayed superconducting-like behaviours |url=https://www.nature.com/articles/d41586-023-02585-7 |journal=Nature |access-date=17 August 2023 |doi=10.1038/d41586-023-02585-7 |date=16 August 2023 |volume=620 |issue=7975 |pages=705–706 |pmid=37587284 |s2cid=260955242 |archive-date=17 August 2023 |archive-url=https://web.archive.org/web/20230817012222/https://www.nature.com/articles/d41586-023-02585-7 |url-status=live }}</ref> was that LK-99 is not a superconductor at room temperature, and is an [[Insulator (electricity)|insulator]] in pure form.<ref name=":15" /><ref>{{Cite web |last=Robinson |first=Dan |title=LK-99 slammed as 'not a superconductor at all' |url=https://www.theregister.com/2023/08/09/lk99_more_physicists_fail_reproduce/ |access-date=2023-08-10 |website=www.theregister.com |language=en |archive-date=10 August 2023 |archive-url=https://web.archive.org/web/20230810063704/https://www.theregister.com/2023/08/09/lk99_more_physicists_fail_reproduce/ |url-status=live }}</ref><ref>{{Cite web |last=Padavic-Callaghan |first=Karmela |title=LK-99: Mounting evidence suggests material is not a superconductor |url=https://www.newscientist.com/article/2386866-lk-99-mounting-evidence-suggests-material-is-not-a-superconductor/ |access-date=2023-08-10 |website=New Scientist |language=en-US |archive-date=9 August 2023 |archive-url=https://web.archive.org/web/20230809230754/https://www.newscientist.com/article/2386866-lk-99-mounting-evidence-suggests-material-is-not-a-superconductor/ |url-status=live }}</ref>

As of 12 February 2024, no replications had gone through the peer review process of a journal, but some had been reviewed by a [[materials science]] lab. A number of replication attempts identified non-superconducting [[ferromagnetic]] and [[diamagnetic]] causes for observations that suggested superconductivity. A prominent cause was a [[Copper(I) sulfide|copper sulfide]] impurity<ref name="Cu2-xS" /> occurring during the proposed synthesis, which can produce [[Electrical resistance and conductance|resistance]] drops, [[lambda transition]] in [[heat capacity]], and magnetic response in small samples.<ref name="Cu2S" /><ref name=":16" /><ref name="Cu2-xS" /><ref name=":17" /><ref name=":3" /><ref name=":10_2" /><ref name="popmech"/>

After the initial preprints were published, Lee claimed they were incomplete,{{r|yonhap-sjho-20230728}} and coauthor Kim Hyun-Tak ({{lang|ko|김현탁}}) said one of the papers contained flaws.<ref name="padavic-c-20230726" />

== Chemical properties and structure ==
The chemical composition of LK-99 is approximately Pb<sub>9</sub>Cu<!--<sub>1</sub>-->(PO<sub>4</sub>)<sub>6</sub>O, in which— compared to pure lead-apatite (Pb<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>O){{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]] ''P''6<sub>3</sub>/''m'' (No. 176).

=== Synthesis ===
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(SO<sub>4</sub>)) powders, and heating at {{convert|725|C|K F|round=10}} for 24 hours<!-- The graph in one paper shows it being performed in a vacuum of 10^-3 torr, but this may be erroneous as the text of the paper gives the reaction as being performed in air. -->:

: PbO + Pb(SO<sub>4</sub>) → Pb<sub>2</sub>(SO<sub>4</sub>)O.

Then, [[copper(I) phosphide]] (Cu<sub>3</sub>P) is produced by mixing copper (Cu) and [[phosphorus]] (P) powders in a 3:1 molar ratio in a sealed tube under a vacuum<!-- One of the arxiv papers gives 10^-3 torr, but the other gives a value of 10^-5 torr --> and heated to {{convert|550|C|K F|sigfig=2}} for 48 hours:{{r|sukbae-2023-2|p=3}}

: 3 Cu + P → Cu<sub>3</sub>P.

Then, lanarkite and copper phosphide crystals are ground into a powder,<!-- The paper published in a Korean journal appears to give a ratio of 1:1, but this may not be correct as other sources say this has a 9:1 ratio of lead to copper atoms. The sample will have many impurities due to this. --> 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}}

:Pb<sub>2</sub>(SO<sub>4</sub>)O + Cu<sub>3</sub>P → Pb<sub>10-{{math|''x''}}</sub>Cu<sub>{{math|''x''}}</sub>(PO<sub>4</sub>)<sub>6</sub>O + 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 [[Chemical equation#Balancing chemical equations|balanced]], and others reported the presence of copper(I) sulfide ({{chem2|Cu2S}}) as well.<ref name="kumar-20230731"/><ref name=":16">{{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 }}</ref> For <math>x=1</math> a balanced reaction might be:

:5 {{chem2|Pb2SO4O + 6 Cu3P → Pb9Cu(PO4)6O + 5 Cu2S + Pb + 7 Cu}}.<ref>{{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 }}</ref>

Many syntheses produced fragmentary results in different phases, where some of the resulting fragments were responsive to magnetic fields, other fragments were not.<ref name=":13" /> The first synthesis to produce pure crystals found them to be diamagnetic insulators.<ref>{{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 }}</ref>

== Physical properties ==
Some small LK-99 samples were reported to show strong diamagnetic properties, including a response confusingly<ref>{{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 }}</ref> referred to as "partial levitation" over a magnet.{{r|sukbae-2023-2}} This was misinterpreted by some as a sign of superconductivity, although it is a sign of regular diamagnetism or ferromagnetism.

While initial preprints claimed the material was a room-temperature superconductor,<ref name="sukbae-2023-2" />{{rp|1}} they did not report observing any definitive features of superconductivity, such as zero resistance, the [[Meissner effect]], [[flux pinning]], [[Magnetic susceptibility#In the frequency domain|AC magnetic susceptibility]], the [[Josephson effect]], a temperature-dependent critical field and current, or a sudden jump in specific heat around the critical temperature.<ref>{{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}}</ref>

As it is common for a new material to spuriously seem like a potential candidate for [[high-temperature superconductivity]],<ref name=":3">{{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}}</ref> thorough experimental reports normally demonstrate a number of these expected properties. {{As of|2023|10|15|post=,}} not one of these properties had been observed by the original experiment or any replications.<ref name="lowe-20230801" />

=== Proposed mechanism for superconductivity ===
Partial replacement of Pb<sup>2+</sup> ions with smaller Cu<sup>2+</sup> 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 ([PO<sub>4</sub>]<sup>3−</sup>). This quantum well was proposed to be superconducting{{r|sukbae-2023|p=10}}, based on a 2021 paper<ref>{{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}}</ref> by Kim Hyun-Tak describing a novel and complicated theory combining ideas from a classical theory of metal-insulator transitions,<ref name=":4">{{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}}</ref> the standard [[Bardeen–Cooper–Schrieffer theory]], and the theory of [[hole superconductivity]]<ref name=":5">{{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}}</ref> by [[Jorge E. Hirsch|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 band potential|flat bands]], and suggesting this might contribute to superconductivity.<ref name="griffin-20230731">{{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}}</ref> 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.<ref name="liang-20230801">{{Cite journal |arxiv=2308.00676 |first1=Liang |last1=Si |first2=Karsten |last2=Held |title=Electronic structure of the putative room-temperature superconductor <math>\text{Pb}_9\text{Cu}(\text{PO}_4)_6\text{O}</math> |journal=Physical Review B |date=2023-08-01|volume=108 |issue=12 |doi=10.1103/PhysRevB.108.L121110 |s2cid=260351297 }}</ref>

Analyses by industrial and experimental physicists noted experimental and theoretical shortcomings of the published works.<ref name=":10" /> Shortcomings included the lack of phase diagrams<ref name=":5" /> spanning temperature, stoichiometry,<ref name=":11">{{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}}</ref> and stress; the lack of pathways for the very high ''T''<sub>c</sub> of LK-99 compared to prior heavy fermion superconductors; the absence of flux pinning in any observations; the possibility of stochastic conductive artifacts<ref name=":12" /> 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==<!--keep #Name for previous incoming links-->
The name LK-99 comes from the initials of discoverers Lee and Kim, and the year of discovery (1999).<ref name="NYTimesLK99Summer"/> 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]].

== Publication history ==
Lee has stated that in 2020, an initial paper was submitted to ''[[Nature (journal)|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.<ref>{{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}}</ref> On 4 April 2023, a Korean trademark application for "LK-99" was filed by the {{nowrap|Q-Centre}}.{{r|trademark}}

=== 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''.{{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 and Telecommunications Research Institute|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}}<ref name=timemag>{{cite web |first=Will |last=Henshall |publisher=[[Time (magazine)|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}}</ref>

On 23 July, the findings were also submitted by Lee to ''[[APL Materials]]'' for [[peer review]].<ref name="chosunbiz-20230727" />{{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.<ref>{{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]]}}</ref>

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.<ref name="kumar-20230731">{{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: Pb<sub>9</sub>Cu(PO<sub>4</sub>)<sub>6</sub>O |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 }}</ref>

On 11 Aug 2023, P. Puphal et al., released their preprint synthesizing the first single crystals of Pb<sub>9</sub>Cu(PO<sub>4</sub>)<sub>6</sub>O finally disproving superconductivity in this chemical stoichiometry published later in [[APL Materials]].<ref name="ReferenceA">{{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 }}</ref>

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 physics|condensed matter]] experimentalist at the [[University of California, Davis]], and several studies previewed in August 2023.<ref name="nature 2023Aug16" />

==== 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.<ref name=":11" /><ref name="timemag" />

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<!--On 28 July 2023-->, [[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.<ref name="NYTimesLK99Summer" /> 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 informed [[Seoul Broadcasting System|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.<ref name=":6">{{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}}</ref>

== Response ==
Materials scientists and superconductor researchers responded with skepticism.{{r|padavic-c-20230726}}<ref name="Nature">{{cite journal |journal=[[Nature 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}}</ref> The [[High-temperature superconductivity|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.<ref name=timemag/><ref name="ked-kim-20230802">{{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}}</ref>

{{As of|2023|08|15|post=,}} 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.{{r|padavic-c-20230726}} A more likely explanation for LK-99's magnetic response is a mix of [[ferromagnetism]] and non-superconductive [[diamagnetism]].<ref name=timemag/><ref name="popmech">{{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}}</ref>{{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.<ref name="Cu2-xS" /><ref name="Cu2S">{{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 }}</ref>

===Public response===
The claims in the 22 July papers by Lee ''et al.'' went [[Viral phenomenon|viral]] on [[social media]] platforms the following week.<ref name=garisto-20230727/><ref name=DIYW/> The viral nature of the claim resulted in posts from users using [[pseudonym]]s from Russia and China claiming to have replicated LK-99 on both [[Twitter]] and [[Zhihu]].<ref name=ferr/> Other [[viral video]]s described themselves as having replicated samples of LK-99 "partially levitating", most of which were found to be fake.<ref name="Nature"/>

Scientists interviewed by the press remained skeptical,<ref name=":7">{{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}}</ref><ref name=":8">{{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/bvj7pm/viral-room-temperature-superconductor-study-lk-99 |access-date=2023-08-02 |first=Jordan |last=Pearson |website=www.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}}</ref> 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 P. Dias#Scientific misconduct investigations|Ranga Dias affair]]).<ref name="timemag" /> The ''Korean Society of Superconductivity and Cryogenics'' expressed concern on the social and economic impacts of the preliminary and unverified LK-99 research.<ref name="TaiNew">{{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}}</ref>

A video from [[Huazhong University of Science and Technology]] uploaded on 1 August 2023 by a postdoctoral researcher on the team of Chang Haixin,<ref name="timemag" /> 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,<ref name="scmp">{{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]]}}</ref><ref name="timemag" /> and a [[prediction market]] briefly put the chance of successful replication at 60%.<ref name="ind2">{{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}}</ref> A researcher from the [[Chinese Academy of Sciences]] refused to comment on the video for the press, dismissing the claim as "ridiculous".<ref name="scmp" />

In early August, people began to create [[internet meme|memes]] about "floating rocks",<ref name="cnet">{{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]]}}</ref> and there was a brief surge in Korean and Chinese technology stocks,<ref>{{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}}</ref><ref>{{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}}</ref><ref name="reu">{{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}}</ref> despite warnings from the [[Korea Exchange|Korean stock exchange]] against speculative bets in light of the excitement around LK-99,<ref name="TaiNew" /> which eventually fell on August 8.<ref name="Bloo89">{{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 }}</ref> Following the publication of the ''Nature'' article on August 16 that proclaimed LK-99 is not a superconductor,<ref name="nature 2023Aug16" /> South Korean superconductor stocks fell further, as the interest about LK-99 from [[investor]]s in previous weeks disappeared.<ref name="KED17">{{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}}</ref>

==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.{{r|garisto-20230727}}

{{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 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<ref name="Cu2-xS" /> 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<ref name="Cu2S" /><ref name="Cu2-xS" /> and a λ-like-feature in the heat capacity.<ref name="Cu2-xS" /> Furthermore, Cu<sub>2</sub>S 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 {{convert|110|K|C F|lk=in}}.<ref name="NYTimesLK99Summer" /><ref name="targ">{{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}}</ref> Doubts were expressed by experts in the field, as they saw no dropoff to zero resistance, and used crude [[ohmmeter|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.<ref name="Nature" /><ref name=":1">{{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}}</ref>

Some replication efforts gained global visibility, with the aid of online replication trackers that catalogued new announcements and status updates.<ref name="ferr">{{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/5d9yez/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}}</ref><ref name="lowe-20230801">{{Cite news |last=Lowe |first=Derek |author-link=Derek Lowe (chemist) |date=2023-08-01 |title=A Room-Temperature Superconductor? New Developments |work=In the pipeline |publisher=[[American Association for the Advancement of Science]] |department=Chemical News |type=blog |url=https://www.science.org/content/blog-post/room-temperature-superconductor-new-developments |url-status=live |access-date=2023-08-01 |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 |via=[[Science (journal)|Science]].org}}</ref>

=== Experimental studies ===
Selected experimental studies.

'''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}}

{| class="wikitable sortable"
!Group
!Country/region
!Status
!Results
!Publication notes
|-
|[[Max Planck Institute for Solid State Research|Max Planck (Solid State)]]
|{{Flag|Germany}}
|{{partial|Preliminary}}
|{{failure|{{†}} Produced pure LK-99 samples with [[Zone melting|floating zone]] technique. Purple crystals with high resistance, no magnetic response.}}
|{{ubl|arXiv:<ref name="ReferenceA">{{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 }}</ref>|Press:<ref name="nature 2023Aug16"/><ref name="Forbes20230818">{{Cite web|first=Alex|last=Knapp|work=[[Forbes]]|date=2023-08-18|access-date=2023-08-18|title=The Rise And Fall Of The Would-Be Superconductor That Transfixed The Internet|url=https://www.forbes.com/sites/alexknapp/2023/08/18/the-rise-and-fall-of-the-would-be-superconductor-that-transfixed-the-internet|archive-date=18 August 2023|archive-url=https://web.archive.org/web/20230818123335/https://www.forbes.com/sites/alexknapp/2023/08/18/the-rise-and-fall-of-the-would-be-superconductor-that-transfixed-the-internet/|url-status=live}}</ref>}}
|-
|[[Huazhong University of Science and Technology|Huazhong Tech]]
| rowspan="6" | {{Flag|China}}
|{{partial|Preliminary}}
|{{partial success|{{asterisk}} Measured diamagnetism of [[micron]]-sized flakes. Non-zero resistance, purity of sample was important.}}
|{{ubl|arXiv:<ref name=":10">{{Cite arXiv |eprint=2308.01516 |class=cond-mat.supr-con |author1=Hao Wu |author2=Li Yang |author3=Bichen Xiao |author4=Haixin Chang |title=Successful growth and room temperature ambient-pressure magnetic levitation of LK-99 |date=2023-08-03}}</ref><ref name=":10_2">{{Cite arXiv |eprint=2308.05001 |class=cond-mat.supr-con |author1=Hao Wu |author2=Li Yang |author3=Jie Yu |author4=Gaojie Zhang |author5=Bichen Xiao |author6=Haixin Chang |title=Observation of abnormal resistance-temperature behavior along with diamagnetic transition in Pb<sub>10−x</sub>Cu<sub>x</sub>(PO<sub>4</sub>)<sub>6</sub>O-based composite |date=2023-08-09}}</ref>|[[bilibili]] video:<ref name=":12">{{Cite web |last=关山口男子技师 |script-title=zh:补充视频_哔哩哔哩_bilibili |url=https://www.bilibili.com/video/BV13k4y1G7i1/ |url-status=live |archive-url=https://web.archive.org/web/20230801154919/https://www.bilibili.com/video/BV13k4y1G7i1/ |archive-date=1 August 2023 |access-date=2023-08-01 |website=www.bilibili.com |language=zh-Hans}}</ref><ref>{{Cite web |last=关山口男子技师 |title=LK-99验证_哔哩哔哩_bilibili |url=https://www.bilibili.com/video/BV14p4y1V7kS/ |url-status=live |archive-url=https://web.archive.org/web/20230801090615/https://www.bilibili.com/video/BV14p4y1V7kS/ |archive-date=1 August 2023 |access-date=2023-08-01 |website=www.bilibili.com |language=zh-Hans}}</ref>|Press:<ref name="lowe-20230801" /><ref name=timemag/><ref name="scmp" /><ref name="ferr" />}}
|-
|[[Beihang University]]
|{{partial|Preliminary}}
|{{failure|{{†}} No diamagnetism observed. High [[resistivity]] not consistent with superconductivity.}}
|{{ubl|arXiv:<ref>{{Cite journal |arxiv=2307.16802 |author1=Li Liu |author2=Ziang Meng |title=Semiconducting Transport in Pb<sub>10−</sub> ''<sub>X</sub>'' Cu ''<sub>x</sub>'' (PO<sub>4</sub>)<sub>6</sub>O Sintered from Pb<sub>2</sub>SO<sub>5</sub> and Cu<sub>3</sub>P |date=2023-07-31 |author3=Xiaoning Wang |author4=Hongyu Chen |author5=Zhiyuan Duan |author6=Xiaorong Zhou |author7=Han Yan |author8=Peixin Qin |author9=Zhiqi Liu|journal=Advanced Functional Materials |doi=10.1002/adfm.202308938 |s2cid=260334279 }}</ref>|Press:<ref name="cnet" /><ref name="tdb">{{Cite web |last=Tran |first=Tony Ho |date=2023-08-01 |title=Sorry, But the New LK-99 Superconductor Breakthrough Might Be Total BS |url=https://www.thedailybeast.com/why-the-room-temperature-lk-99-superconductor-might-be-total-bs |url-status=live |archive-url=https://web.archive.org/web/20230801224658/https://www.thedailybeast.com/why-the-room-temperature-lk-99-superconductor-might-be-total-bs |archive-date=1 August 2023 |access-date=2023-08-02 |website=www.thedailybeast.com |publisher=[[The Daily Beast]]}}</ref>}}
|-
|[[Southeast University]]
|{{partial|Preliminary}}
|{{Partial success|{{asterisk}} Structure confirmed by [[x-ray crystallography|XRD]]. Resistance of one mm-sized sample dropped from 0.1&nbsp;Ω at room temperature to noise level (10<sup>−5</sup>&nbsp;Ω) at 110&nbsp;K and below. No observed Meissner effect.}}
|{{ubl|arXiv:<ref name=":2">{{Cite journal |arxiv=2308.01192 |first1=Qiang |last1=Hou |first2=Wei |last2=Wei |first3=Xin |last3=Zhou |first4=Yue |last4=Sun |first5=Zhixiang |last5=Shi |date=2023-08-02 |title=Synthesis, transport and magnetic properties of Cu-doped apatite Pb10−Cu (PO4)6O |journal=Matter |volume=6 |issue=12 |pages=4408–4418 |doi=10.1016/j.matt.2023.11.014 }}</ref><ref name=":hou2">{{Cite journal |arxiv=2308.05778 |first1=Qiang |last1=Hou |first2=Wei |last2=Wei |first3=Xin |last3=Zhou |first4=Xinyue |last4=Wang |first5=Yue |last5=Sun |first6=Zhixiang |last6=Shi |date=2023-08-02 |title=Synthesis, transport and magnetic properties of Cu-doped apatite Pb10−Cu (PO4)6O |journal=Matter |volume=6 |issue=12 |pages=4408–4418 |doi=10.1016/j.matt.2023.11.014 }}</ref>|Video:<ref name="targ"/>|Critics:<ref name="Nature"/><ref name=":1" />|Press:<ref name="NYTimesLK99Summer"/>}}
|-
|[[Peking University]]
|{{partial|Preliminary}}
|{{failure|{{†}} No Meissner effect nor zero resistivity observed.}}
|{{ubl|arXiv:<ref>{{Cite journal |arxiv=2308.03110 |author1=Kaizhen Guo |author2=Yuan Li |author3=Shuang Kia |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 }}</ref>|Press:<ref name="nature 2023Aug16"/>}}
|-
|[[Chinese Academy of Sciences]] (Condensed Matter)
|{{partial|Preliminary}}
|{{failure|{{†}} No superconductivity observed. Proposed that resistivity drop and strong diamagnetism could be due to a phase change of [[Copper(I) sulfide|Cu<sub>2</sub>S]] impurities.}}
|{{ubl|arXiv:<ref name="Cu2S"/>|Press:<ref name="nature 2023Aug16"/><ref name="Forbes20230818"/>}}
|-
|[[Central South University]], [[South China University of Technology|South China Tech]], and [[University of Electronic Science and Technology of China|UESTC]]
|{{partial|Preliminary}}
|{{partial success|{{asterisk}} Low-field microwave absorption below 250&nbsp;K resembles superconductivity, but is destroyed by rotation in an external field.  Theoretical models suggest the external field excites a fragile superconducting state to a [[vortex glass]], followed by a ~2-day-long relaxation to the ground state.}}
|{{ubl|arXiv:<ref name=":9">{{Cite arXiv |eprint=2312.10391 |class=cond-mat |author=Jicheng Liu |author2=Chenao He |title=Strange memory effect of low-field microwave absorption in copper-substituted lead apatite |collaboration=Weijie Huang, Zhihao Zhen, Guanhua Chen, Tianyong Luo, Xianfeng Qiao, Yao Yao, Dongge Ma |date=2023-12-16 |language=en}}</ref>}}
|-
|[[Dipc|DIPC]], [[Princeton University|Princeton]], [[Max Planck Institute for Chemical Physics of Solids|Max Planck (Chemical Physics)]]
|{{Flag|Spain}}, {{Flag|USA}}, {{Flag|Germany}}
|{{partial|Preliminary}}
|{{failure|{{†}} Synthesized LK-99 found to be a multiphase material. Performed single-crystal analysis with XRD. Tested four different Cu dopings, some found to be magnetic but none was superconducting.}}
|{{ubl|arXiv:<ref>{{Cite arXiv |date=August 8, 2023 |title=Pb9Cu(PO4)6(OH)2: Phonon bands, Localized Flat Band Magnetism, Models, and Chemical Analysis |class=cond-mat.supr-con |eprint=2308.05143 |last1=Jiang |first1=Yi |last2=Lee |first2=Scott B. |last3=Herzog-Arbeitman |first3=Jonah |last4=Yu |first4=Jiabin |last5=Feng |first5=Xiaolong |last6=Hu |first6=Haoyu |last7=Călugăru |first7=Dumitru |last8=Brodale |first8=Parker S. |last9=Gormley |first9=Eoghan L. |author10=Maia Garcia Vergniory |last11=Felser |first11=Claudia |last12=Blanco-Canosa |first12=S. |last13=Hendon |first13=Christopher H. |last14=Schoop |first14=Leslie M. |last15=Andrei Bernevig |first15=B. }}</ref>|Press:<ref name="nature 2023Aug16"/><ref name="Forbes20230818"/>}}
|-
|[[University of Manchester]]
|{{Flag|United Kingdom}}
|{{partial|Preliminary}}
|{{failure|{{†}} Synthesized and characterized samples of LK-99, no superconductivity.}}
|{{ubl|arXiv:<ref>{{Cite arXiv |eprint=2308.03823 |class=cond-mat.supr-con |first1=Ivan |last1=Timokhin |first2=Chuhongxu |last2=Chen |first3=Qian |last3=Yang  |first4=Artem |last4=Mishchenko|title=Synthesis and characterisation of LK-99 |date=2023-08-07}}</ref>}}
|-
|[[National Physical Laboratory of India|CSIR-NPLI]]
|{{Flag|India}}
|{{partial|Preliminary}}
|{{partial success|{{asterisk}} Initial attempt: Structure confirmed by XRD, no diamagnetism or superconductivity.
Second attempt: strong diamagnetism in a fragment.}}
|{{ubl|Video:<ref>{{cite web|website=[[Facebook]]|url=https://www.facebook.com/100008122782686/videos/661722942350287|author=V.P.S Awana|date=2023-08-10|access-date=2023-08-10|title=LK-99 VIDEO|archive-date=10 August 2023|archive-url=https://web.archive.org/web/20230810112413/https://www.facebook.com/100008122782686/videos/661722942350287/|url-status=live}}</ref>|arXiv:<ref name="kumar-20230731" /><ref>{{Cite web |title=People@CSIR-NPL – NPL |url=https://www.nplindia.org/index.php/peoplecsir-npl/ |access-date=2023-07-31 |language=en |archive-date=8 June 2023 |archive-url=https://web.archive.org/web/20230608193251/https://www.nplindia.org/index.php/peoplecsir-npl/ |url-status=live}}</ref><ref>{{Cite web |title=Dr. V.P.S. Awana, PhD - Editorial Board - Superconductivity - Journal - Elsevier |url=https://www.journals.elsevier.com/superconductivity/editorial-board/dr-vps-awana-phd |access-date=2023-07-31 |website=www.journals.elsevier.com |archive-date=3 August 2023 |archive-url=https://web.archive.org/web/20230803191711/https://www.journals.elsevier.com/superconductivity/editorial-board/dr-vps-awana-phd |url-status=live}}</ref>|Press:<ref name=timemag/><ref name="cnet" /><ref name="ferr" /><ref name="tdb" />}}
|-
|[[Varda Space Industries|Varda Space]] & [[University of Southern California|USC]]
|rowspan="3"|{{Flag|United States}}
|{{partial|Preliminary}}
|{{failure|{{†}} Only a few LK-99 fragments responded to magnetic field.
Analysis showed impurities of Iron and Cu<sub>2</sub>S, which could explain magnetic response rather than superconductivity.}}
|{{ubl|Videos:<ref>{{Cite twitter |number=1687405505604734978 |user=andrewmccalip |title=Meissner effect or bust: Day 8.5 |access-date=2023-08-04 |language=en}}</ref><ref>{{Cite twitter |number=1688082372250755072 |user=andrewmccalip |title=[untitled] |access-date=2023-08-06 |language=en}}</ref><ref>{{Cite twitter |number=1685871360948748288 |user=andrewmccalip |title=Meissner effect or bust: Day 4 |access-date=2023-08-01 |language=en}}</ref><ref name=":17">{{Cite twitter |number=1689476909208600576 |user=andrewmccalip |title=Meissner Effect or Bust: Day 12 |language=en}}</ref>|Press:<ref name="Forbes20230818"/><ref name=timemag/><ref name="ferr" /><ref name=DIYW>{{cite magazine |last1=Barber |first1=Gregory |date=2023-08-02 |title=Inside the DIY Race to Replicate LK-99 |url=https://www.wired.com/story/inside-the-diy-race-to-replicate-lk-99/ |url-status=live |archive-url=https://web.archive.org/web/20230802143413/https://www.wired.com/story/inside-the-diy-race-to-replicate-lk-99/ |archive-date=2 August 2023 |access-date=2 August 2023 |magazine=Wired}}</ref>}}
|-
|[[University of Colorado Boulder|UC–Boulder]]
|{{unknown|Unpublished}}
|{{failure|{{†}} Samples have failed tests for superconductivity.}}
|{{ubl|Press:<ref name=":15">{{cite news|url=https://www.washingtonpost.com/science/2023/08/09/room-temperature-superconductor-lk99-evidence/|newspaper=[[The Washington Post]]|first=Carolyn Y.|last=Johnson|title=A superconductor claim blew up online. Science has punctured it.|date=2023-08-09|access-date=2023-08-09|archive-date=9 August 2023|archive-url=https://web.archive.org/web/20230809215311/https://www.washingtonpost.com/science/2023/08/09/room-temperature-superconductor-lk99-evidence/|url-status=live}}</ref>}}
|-
|[[Argonne National Laboratory|Argonne]]
|{{unknown}}
|{{n/a|Not reported}}
|{{ubl|Press:<ref name=timemag/><ref name="cho-20230727" /><ref name="ferr" />}}
|-
|[[Korea University]], [[Sungkyunkwan University]], [[Seoul National University]]
|rowspan="1"|{{Flag|South Korea}}
|{{unknown}}
|{{n/a|Not reported}}
|{{ubl|Press:<ref name=timemag/><ref name="ked-kim-20230802" />}}
|-
|[[Chinese Academy of Sciences]] (Process Engineering), [[South China University of Technology|South China Tech]], [[Beijing 2060 Technology Co., Ltd.|Beijing 2060]], [[Huazhong University of Science and Technology|Huazhong Tech]], [[Fuzhou University]], [[Tokai University]], and [[University of Science and Technology Beijing|USTB]]
| rowspan="2" |{{CHNML}}、{{JAP}}
|{{partial|Preliminary}}
|{{Partial success|{{asterisk}} Modified LK-99 exhibited diamagnetic direct current magnetization occurred under a 25&nbsp;Oe magnetic field, but significant bifurcation between zero field cooling (ZFC) and field cooling (FC) measurements, and paramagnetism at a 200&nbsp;Oe magnetic field. A glassy memory effect was discovered while cooling. Typical hysteresis loops of superconductors were detected below 250&nbsp;K, and there was asymmetry between forward and reverse magnetic field scans. Possible Meissner effect at room temperature.}}
|{{ubl|Press:<ref>{{Cite web|title=科技周报{{!}}国内发现疑似室温超导新材料、比亚迪销量超特斯拉_腾讯新闻|url=https://new.qq.com/rain/a/20240105A088TQ00|access-date=2024-01-08|website=new.qq.com|date=5 January 2024 }}</ref><ref>{{Cite web|title=又导了?中科院等发现新疑似室温超导材料, 作者: 对结果很有信心_澎湃号·湃客_澎湃新闻-The Paper|url=https://www.thepaper.cn/newsDetail_forward_25898448|access-date=2024-01-08|website=www.thepaper.cn}}</ref>|arXiv:<ref name=":0">{{Cite arXiv |eprint=2401.00999 |author=Hongyang Wang |author2=Yao Yao |title=Possible Meissner effect near room temperature in copper-substituted lead apatite |collaboration=Ke Shi, Yijing Zhao, Hao Wu, Zhixing Wu, Zhihui Geng, Shufeng Ye, Ning Chen |date=2024-01-02 |class=cond-mat.supr-con |language=en}}</ref>|Q&As:<ref>
{{Cite web
|title=如何看待「真可爱呆」等人论文(2401.00999)发现可能的近室温迈斯纳效应(疑似室温超导)?
|url=https://www.zhihu.com/question/637763289/answer/3347898701
|date= 2024-01-03
|author = Hongyang Wang
|access-date=2024-01-16
|website=[[Zhihu]]
|url-status=live
|language=zh-cn
| archiveurl  = https://archive.today/20240103082305/https://www.zhihu.com/question/637763289/answer/3347898701
| archivedate = 2024-01-03
|trans-title=How to view the possible near room temperature Meisner effect (suspected of room temperature superconductivity) discovered in the paper by "Truly Cute and Stupid" and others (2401.00999)?
}}
</ref><ref>
{{Cite web
|title=如何看待「真可爱呆」等人论文(2401.00999)发现可能的近室温迈斯纳效应(疑似室温超导)?
|url=https://www.zhihu.com/question/637763289/answer/3347895981
|access-date=2024-01-16
|author = Yao Yao
|date= 2024-01-03
|url-status=live
|website=[[Zhihu]]
| archiveurl  = https://archive.today/20240103082258/https://www.zhihu.com/question/637763289/answer/3347895981
| archivedate = 2024-01-03
|trans-title=How to view the possible near room temperature Meisner effect (suspected of room temperature superconductivity) discovered in the paper by "Truly Cute and Stupid" and others (2401.00999)?
|language=zh-cn
}}
</ref><ref>
{{Cite web
|title=如何看待「真可爱呆」等人论文(2401.00999)发现可能的近室温迈斯纳效应(疑似室温超导)?
|url=https://www.zhihu.com/question/637763289/answer/3347887710
|access-date=2024-01-16
|author = Zhihui Geng
|date= 2024-01-03
| archiveurl  = https://archive.today/20240103082249/https://www.zhihu.com/question/637763289/answer/3347887710
| archivedate = 2024-01-03
|url-status=live
|website=[[Zhihu]]
|trans-title=How to view the possible near room temperature Meisner effect (suspected of room temperature superconductivity) discovered in the paper by "Truly Cute and Stupid" and others (2401.00999)?
|language=zh-cn
}}</ref>}}
|-
|[[Chinese Academy of Sciences]] (Process Engineering), [[Huazhong University of Science and Technology]] , [[University of Science and Technology Beijing]], [[South China University of Technology]], [[Fuzhou University]], [[Tokai University]] and [[University of Science and Technology of China]]
|{{partial|Preliminary}}
|{{partial|{{asterisk}} 1. Proposed a new LK-99 structure theory
2. The resistance of LK-99 material was measured, which is roughly equivalent to copper.

3. Observed [[Fermi liquid theory#Non-Fermi liquids|strange metal phenomena]]}}
|arXiv:[https://arxiv.org/html/2403.11126v1 Observation of diamagnetic strange-metal phase in sulfur-copper codoped lead apatite]
|}

=== 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.

Selected theoretical studies:

{| class="wikitable sortable"
!Group
!Country
!Result
!Publication notes
|-
|[[Chinese Academy of Sciences]] (SYNL)
|{{Flag|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.<ref>{{Cite journal |arxiv=2307.16040 |first1=Junwen |last1=Lai |first2=Jiangxu |last2=Li |title=First-principles study on the electronic structure of Pb<sub>10−''x''</sub>Cu<sub>''x''</sub>(PO<sub>4</sub>)<sub>6</sub>O (''x'' = 0, 1) |date=29 Jul 2023 |last3=Liu |first3=Peitao |last4=Sun |first4=Yan |last5=Chen |first5=Xing-Qiu |journal=Journal of Materials Science & Technology |volume=171 |pages=66–70 |doi=10.1016/j.jmst.2023.08.001 }}</ref>''
Media mentions:<ref>{{cite news |date=1 August 2023 |title=Breakthrough in Superconductivity: Huazhong University Scientists Report First Successful Replication of LK-99 |work=Beijing Times |url=https://beijingtimes.com/china/2023/08/01/breakthrough-in-superconductivity-huazhong-university-scientists-report-first-successful-replication-of-lk-99/ |url-status=live |access-date=2 August 2023 |archive-url=https://web.archive.org/web/20230802153951/https://beijingtimes.com/china/2023/08/01/breakthrough-in-superconductivity-huazhong-university-scientists-report-first-successful-replication-of-lk-99/ |archive-date=2 August 2023}}</ref>
|-
|Lawrence Berkeley National Laboratory
|{{Flag|United States}}
|Density functional theory analysis on a simplified 3D structure explored possible electronic structure that could favor superconductivity, suggests slightly decreased lattice constant.
Similar work published the next day by Si & Held<ref name="liang-20230801" /> and Kurleto, ''et al.''<ref name="kurleto-20230801">{{Cite arXiv |eprint=2308.00698 |class=cond-mat.supr-con |first1=Rafal |last1=Kurleto |first2=Stephan |last2=Lany |title=Pb-apatite framework as a generator of novel flat-band CuO based physics, including possible room temperature superconductivity |date=2023-08-01 |last3=Pashov |first3=Dimitar |last4=Acharya |first4=Swagata |last5=van Schilfgaarde |first5=Mark |last6=Dessau |first6=Daniel S.}}</ref>
|arXiv: [[Sinéad Griffin]]<ref name="griffin-20230731" /><ref name="dft" group="b" /> Analysis:<ref>{{Cite twitter |number=1686659102674751488 |user=sineatrix |author-link=Sinéad Griffin |title=a monster thread on what my paper says, the approximations and the caveats |author=Sinéad Griffin |access-date=2023-08-03 |language=en}}</ref><ref>{{Cite twitter |number=1686373899662213123 |user=condensed_the |title=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 |author=Condensed Matter Theory Center, UMD |access-date=2023-08-02 |language=en}}</ref>
Media mentions:<ref name="ind2" /><ref name="cnet" />
|-
|[[University of Chile|Universidad de Chile]]
|{{Flag|Chile}}
|DFT analysis, finding large electron-phonon coupling in the flat bands.
|arXiv: J. Cabezas-Escares, ''et al.''<ref>{{Cite journal |last=Cabezas-Escares |first=J |title=Electronic structure and vibrational stability of copper-substituted lead apatite LK-99 |journal=Physical Review B |date=2024 |volume=109 |issue=14 |page=144515 |doi=10.1103/PhysRevB.109.144515 |arxiv=2308.01135|bibcode=2024PhRvB.109n4515C }}</ref>
|-
|[[CIEMAT]]
| {{comma separated entries|{{Flag|Spain}}|{{Flag|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''.<ref name=":13">{{Cite journal |last1=Abramian |first1=P. |last2=Kuzanyan |first2=A. |last3=Nikoghosyan |first3=V. |last4=Teknowijoyo |first4=S. |last5=Gulian |first5=A. |date=2023 |title=Some Remarks on Possible Superconductivity of Composition Pb9CuP6O25 |journal=Optical Memory and Neural Networks |volume=32 |pages=S424–S427 |doi=10.3103/S1060992X23070020 |arxiv=2308.01723}}</ref>
|-
|[[Northwest University (China)]] and [[TU Wien]]
|{{comma separated entries|{{Flag|China}}|{{Flag|Austria}}}}
|Concludes {{Chem2|Pb9Cu(PO4)6O}}, without further doping, is an insulator. Analyzes possible effects of doping.
|arXiv: Liang Si & Karsten Held<ref name="liang-20230801" /><ref name="dft" group="b" />
|-
|[[Indiana University Bloomington]]
|{{Flag|United States}}
|Concludes material is a transparent insulator, possibly with active Cu color centers at low temperature. Does not find signatures of type I or II superconductivity. Solves previous issues related to overestimation of lattice constant contraction, doping site energetics. Does not find flat bands at Fermi level, concluding they are related to an unfavored high-symmetry structure.
|arxiv: [https://georgescu.lab.indiana.edu/ A.B. Georgescu]<ref>{{Cite arXiv |last=Georgescu |first=Alexandru B. |date=2023 |title=Cu-doped Pb<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>O, and V doped SrTiO<sub>3</sub> -- a tutorial on electron-crystal lattice coupling in insulating materials with transition metal dopants |class=cond-mat.str-el |eprint=2308.07295}}</ref> Analysis and discussions:<ref>{{Cite twitter |user=AlexandruBG |number= 1689735667041861633 |title= So here's some results on LK-99 as a tutorial case example in electron-lattice interactions. So here's my two main results on it. Just very isolated, S=1/2, Cu bands in an insulator. Nothing at the Fermi level in DFT+U. One can also think of these as color centers. |access-date=2023-08-28 |language=en}}</ref><ref>{{Cite twitter |user=AlexandruBG |number=1691876959737762172 |title=Nice. Theory can be pretty predictive at times. |access-date=2023-08-28 |language=en}}</ref>
|}

{{reflist|group="b"|refs=
<ref name="dft">The first three [[density functional theory]] analyses were published within 24 hours of one another, and have largely overlapping analysis.</ref>
}}

== See also ==
* [[Bismuth strontium calcium copper oxide]]: Superconductivity at ''T''<sub>c</sub> ≈ {{convert|33|K|C}} to {{convert|104|K|C}}
* [[Carbonaceous sulfur hydride]]: Purported superconductivity at ''T''<sub>c</sub> ≈ {{convert|288|K|C}} at 267 [[Pascal (unit)|GPa]]
* [[Lanthanum decahydride]]: Superconductivity at ''T''<sub>c</sub> = {{convert|250|K|C}} at 150 GPa
* [[Unconventional superconductor]]
* [[Salvatore Pais]] – Inventor with a patent referenced by a patent related to LK-99

==References==
{{reflist|refs=
<ref name="NYTimesLK99Summer">{{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}}</ref>
<ref name="patent-2020">{{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}}</ref>
<ref name="patent-2021">{{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}}</ref>
<ref name="sukbae-2023b">{{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}}</ref>
<ref name="trademark">{{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}}</ref>
* <ref name="garisto-20230725">{{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 (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}}</ref>
<ref name="sukbae-2023">{{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}}</ref>
<ref name="sukbae-2023-2">{{cite arXiv |title=Superconductor Pb<sub>10−x</sub>Cu<sub>x</sub>(PO<sub>4</sub>)<sub>6</sub>O 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}}</ref>
* <ref name="ritchie-20230726">{{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 (newspaper)|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 (newspaper)|i]]'' that it, and other data in the paper, "could stem from other phenomena". [[Graphene]], ... "is also [[diamagnetism|diamagnetic]] [displaying repulsion like a superconductor] and can produce weak levitation". The video, in other words, could have a non-superconductor explanation.}}</ref>
* <ref name="padavic-c-20230726">{{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}}</ref>
* <ref name="garisto-20230727">{{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}}<!-- only uses Kelvin + Fahrenheit! --></ref>
<ref name="Cu2-xS">{{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 }}</ref>
* <ref name="chosunbiz-20230727">{{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=[[The Chosun Ilbo|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 [[Nature (journal)|네이처]]에 제출했지만 [[Ranga P. Dias|다이어스 교수]] 사태 때문에 [[Nature (journal)|네이처]]가 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 '[[APL Materials|ALP 머터리얼즈]]'에도 논문을 제출했다고 덧붙였다. 세계적인 물리학 저널에 인정을 받겠다는 설명이다. ... "지금은 작고한 [[:ko:최동식|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}}</ref>
* <ref name="kwon-20230728">{{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}}</ref>
* <ref name="seifert-20230728">{{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.}}</ref>
* <ref name="bodin-20230728">{{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}}</ref>
* <ref name="yonhap-sjho-20230728">{{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 "[[arXiv|아카이브]]에 내려달라는 요청을 해둔 상황" 이라고 주장했다. ... 이 대표는 권 연구교수가 퀀텀에너지연구소 최고기술책임자(CTO)로 있었지만 4개월 전 이사직을 내려놓고 현재는 회사와 관련이 없다고도 밝혔다. ... [[Korea University|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}}</ref>
* <ref name="cho-20230727">{{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}}</ref>
<!--<ref name="chair-1994">{{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}}</ref>  -->
}}

==Further reading==
{{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 Pb<sub>4</sub>O(PO<sub>4</sub>)<sub>2</sub>, Pb<sub>8</sub>O<sub>5</sub>(PO<sub>4</sub>)<sub>2</sub> and Pb<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>O |date=2002-10-17|<!--access-date=2023-07-29|-->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=[[:de:R. Oldenbourg Verlag|Oldenbourg Wissenschaftsverlag]] |location=Munich |s2cid=101229927 |quote=The compound Pb<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>O has been designated 'oxypyromorphite' ... Pb<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>O crystallizes with an [[apatite]]-type structure. The structure contains a single [[Oxygen|O]] atom that is not part of a PO<sub>4</sub> tetrahedron; it has a site occupancy factor of 0.25 and is located on the 6<sub>3</sub> 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 (journal)|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}} <!-- only uses Fahrenheit!! -->
* {{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=[[Nanjing University|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<!--吴跃伟--> |author2=Sun, Wenya<!--孙雯雅--> |author3=Li, Ruiyang<!--李瑞阳--> |quote=<!--Professor Wen Haihu from [[Nanjing University]] is being quoted heavily, but there is nothing in the article claiming/suggesting any attempt at replication at [[Nanjing University]]!--> }}
* {{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=[[:ko:디지털타임스|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<!--|access-date=2023-08-16-->|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<!--|access-date=2023-08-16-->|volume=11 |issue=10 |doi=10.1063/5.0172755 |bibcode=2023APLM...11j1128P |s2cid=260866146 }}
{{refend}}

==External links==
* {{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<sub>10−x</sub>Cu<sub>x</sub>(PO<sub>4</sub>)<sub>6</sub>O 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]]