LK-99

LK-99

3D structure
Identifiers
  • InChI=1S/Cu.6H3O4P.O.9Pb/c;6*1-5(2,3)4;;;;;;;;;;/h;6*(H3,1,2,3,4);;;;;;;;;;/q+2;;;;;;;-2;9*+2/p-18
    Key: KZSIWLDFTIMUEG-UHFFFAOYSA-A
  • [Pb+2].[Pb+2].[Pb+2].[Pb+2].[Pb+2].[Pb+2].[Pb+2].[Pb+2].[Pb+2].[Cu+2].O=P([O-])([O-])[O-].O=P([O-])([O-])[O-].O=P([O-])([O-])[O-].O=P([O-])([O-])[O-].O=P([O-])([O-])[O-].O=P([O-])([O-])[O-].[O-2]
Properties
CuO25P6Pb9
Molar mass 2514.2 g·mol−1
Appearance Purple crystal when pure[1]
Density ≈6.699 g/cm3
Structure
hexagonal
P63/m, No. 176
a = 9.843 Å, c = 7.428 Å
623.2 Å3
1
Related compounds
Related compounds
 Oxypyromorphite (lead apatite)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

LK-99 (from the Lee-Kim 1999 research),[2] also called PCPOSOS,[3] is a gray–black, polycrystalline compound, identified as a copper-doped lead‒oxyapatite. A team from Korea University led by Lee Sukbae (이석배) and Kim Ji-Hoon (김지훈) began studying this material as a potential superconductor starting in 1999.[4]: 1  In July 2023, they published preprints claiming that it acts as a room-temperature superconductor[4]: 8  at temperatures of up to 400 K (127 °C; 260 °F) at ambient pressure.[2][5][4]: 1 

Many different researchers have attempted to replicate the work, and were able to reach initial results within weeks, as the process of producing the material is relatively straightforward.[6] By mid-August 2023, the consensus[1] was that LK-99 is not a superconductor at room temperature, and is an insulator in pure form.[7][8][9]

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 sulfide impurity[10] occurring during the proposed synthesis, which can produce resistance drops, lambda transition in heat capacity, and magnetic response in small samples.[11][12][10][13][14][15][16]

After the initial preprints were published, Lee claimed they were incomplete,[17] and coauthor Kim Hyun-Tak (김현탁) said one of the papers contained flaws.[18]

  1. ^ a b Garisto, Dan (16 August 2023). "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". Nature. 620 (7975): 705–706. doi:10.1038/d41586-023-02585-7. PMID 37587284. S2CID 260955242. Archived from the original on 17 August 2023. Retrieved 17 August 2023.
  2. ^ a b Cite error: The named reference NYTimesLK99Summer was invoked but never defined (see the help page).
  3. ^ Bulletin of the American Physical Society, March 2024 meeting notice
  4. ^ a b c Cite error: The named reference sukbae-2023 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference sukbae-2023b was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference garisto-20230727 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference :15 was invoked but never defined (see the help page).
  8. ^ Robinson, Dan. "LK-99 slammed as 'not a superconductor at all'". www.theregister.com. Archived from the original on 10 August 2023. Retrieved 10 August 2023.
  9. ^ Padavic-Callaghan, Karmela. "LK-99: Mounting evidence suggests material is not a superconductor". New Scientist. Archived from the original on 9 August 2023. Retrieved 10 August 2023.
  10. ^ a b Cite error: The named reference Cu2-xS was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Cu2S was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference :16 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference :17 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference :3 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference :10_2 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference popmech was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference yonhap-sjho-20230728 was invoked but never defined (see the help page).
  18. ^ Cite error: The named reference padavic-c-20230726 was invoked but never defined (see the help page).