[dr_zoidberg]

> It means LK99 is about as good as the other materials, at minimum. However, its chemical composition is different than any of the other materials on the chart (i.e. it is lead based)

While what you say is correct, let's not forget that lead _is_ an elemental superconductor. With a Tc of 7K, it's only bested by niobium (9K) and diamond (11K) as an elemental superconductor.

Yes, cuprates and ceramics were ruling high-temperature SC so far, but it's not like lead was entirely unexpected in the superconducting world.