Structural and Electronic Intricacies of Cu-Doped Lead Apatite (LK-99): Implications for Potential Ambient-Pressure Superconductivity

The Journal of Physical Chemistry C

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Copyright © 2023 American Chemical Society

Abstract

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The most recent discovery, the Cu-doped lead apatite “LK-99”, is a proposed room-temperature superconductor operating under ambient pressure. However, this discovery has brought a slew of conflicting results from different scientific groups. While some observed the absence of electrical resistance, others could not confirm any signs of superconductivity in LK-99. Here, we investigate the structural and electronic properties of LK-99 and its antecedent compounds through quantum mechanics (QM) and QM-based molecular dynamics (QM-MD) simulations. Our study elucidates the insulating nature of base compounds, Pb₁₀(PO₄)₆O and Pb₁₀(PO₄)₆(OH)₂, spotlighting their large band gaps. Notably, Cu doping in LK-99 disrupts its symmetry, yielding a distorted ground-state crystal structure with a triclinic P1 symmetry and CuO₄ square coordination. Such alterations predispose LK-99 to exhibit semiconducting behaviors, characterized by a flat band above the Fermi energy, arising from Cu-3d and O-2p orbitals. In addition, the S doping sustains the triclinic P1 symmetry but leads to a significantly reduced band gap, with a band emerging primarily from Cu-3d and S-3p orbitals. These findings are important in understanding LK-99’s structural and electronic properties and provide a strategic compass for the development of high-T_C superconductors.

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This article is cited by 5 publications.

1. Guoliang Liu, Xiyue Cheng, Minwei Xiang, Zhian Li, Shuiquan Deng. Pb 9 Cu(PO 4 ) 6 O: a room-temperature superconductor? electronic-structure features assessed via the flat/steep band model. RSC Advances 2025, 15 (59) , 51124-51135. https://doi.org/10.1039/D5RA07404E
2. Meera P Reghunath, Ramaswamy Murugavel. Unraveling an Organic Soluble Precursor‐Based Low‐Temperature Synthetic Strategy to Impurity‐Free Pristine and Transition Metal Doped Lead Apatites. Chemistry – A European Journal 2025, 31 (61) https://doi.org/10.1002/chem.202501888
3. I V Sukhenko, V L Karbivskyy. Reflecting on the LK-99 fervour: insights and future prospects. Journal of Physics: Condensed Matter 2025, 37 (8) , 083002. https://doi.org/10.1088/1361-648X/ad9804
4. Yibo Liu, Changzeng Fan, Bing Zhang, Bin Wen, Lifeng Zhang. The Crystal Structure of Apatite and Copper-Doped Apatite. Green Chemical Technology 2025, 2 (2) , 10005-10005. https://doi.org/10.70322/gct.2025.10005
5. J. Cabezas-Escares, Nicolás F. Barrera, Robert H. Lavroff, Anastassia N. Alexandrova, C. Cardenas, F. Munoz. Electronic structure and vibrational stability of copper-substituted lead apatite LK-99. Physical Review B 2024, 109 (14) https://doi.org/10.1103/PhysRevB.109.144515

Cite this: J. Phys. Chem. C 2024, 128, 1

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Published December 22, 2023

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