LK-99 also called PCPOSOS, is a gray–black, polycrystalline compound, identified as a copper-doped lead‒oxyapatite. A team from Korea University led by Lee Sukbae () and Kim Ji-Hoon () began studying this material as a potential superconductor, and in July 2023 published preprints claiming that it acted as a room-temperature superconductor at temperatures of up to at ambient pressure.
Many different researchers attempted to replicate the work, and were able to reach initial results within weeks, as the process of producing the material is relatively straightforward. By mid-August 2023, the consensus was that LK-99 is not a superconductor at room temperature, and is an insulator in pure form.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).