3D structure
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Identifiers | |
---|---|
| |
| |
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
| |
Lattice volume (V)
|
623.2 Å3 |
Formula units (Z)
|
1 |
Related compounds | |
Related compounds
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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]
NYTimesLK99Summer
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