What happened with the LK-99 room-temperature superconductor claim?

The answer

In July 2023, South Korean researchers Sukbae Lee and Ji-Hoon Kim published preprints claiming LK-99, a lead-apatite compound doped with copper, was a room-temperature, ambient-pressure superconductor. The announcement electrified social media and labs worldwide rushed to replicate the findings. Within weeks, multiple independent teams - including groups at Argonne National Laboratory, the Max Planck Institute, and Peking University - failed to reproduce superconductivity. Analysis revealed the observed properties were caused by copper sulfide (Cu₂S) impurities creating a resistivity drop, not superconductivity. The episode highlighted both the extraordinary desire for such a breakthrough and the robust self-correcting nature of the scientific process.