LK-99 isn’t a superconductor — how science sleuths solved the mystery

Boo!

Efforts to replicate the material have pieced together the puzzle of why it displayed superconducting-like behaviours. […] The conclusion dashes hopes that LK-99 — a compound of copper, lead, phosphorus and oxygen — would prove to be the first superconductor that works at room temperature and ambient pressure. Instead, studies have shown that impurities in the material — in particular, copper sulfide — were responsible for sharp drops in its electrical resistivity and a display of partial levitation over a magnet, properties similar to those exhibited by superconductors.