The dream appears to be over. After a few intense weeks of speculation and drama, more and more labs have been able to recreate LK-99, also known as modified lead-apatite. The material was touted as the first-ever room-temperature ambient pressure superconductor, a claim that was met with healthy skepticism and excitement. After all, extraordinary claims require extraordinary evidence.
Unfortunately, the evidence has failed to materialize. Labs have reproduced the material following the original paper's instructions and, in newly uploaded papers, they have not found any evidence of superconductivity. Actually, quite the opposite.
Superconductivity begins at a critical temperature below which the material can transmit electricity with no resistance. According to some of the new data, the resistivity of LK-99 increases as you lower the temperature, like some sort of anti-superconductor.
“When we are measuring superconductors, the most obvious property of a superconductor is zero resistance,” Professor Susie Speller, from the Oxford Centre for Applied Superconductivity, told IFLScience in a previous deep-dive on LK-99. “What you look for is for the material to have some resistance. You cool it down, and suddenly it should lose that resistance, and it should be absolutely zero when it's in the superconducting state. You should see a very clear change in resistance at the temperature where it starts to superconduct.”
Other measurements that were expected to be seen were a dramatic shift in heat capacity at the critical temperature and the change from being non-magnetic to being diamagnetic. The diamagnetism was seen in several videos (although a paper claims it is ferromagnetism) but by itself it is not as interesting. Lots of materials are diamagnetic without many revolutionary applications.
While the development is certainly disappointing, materials science continues to make breakthroughs in superconductivity. New materials are expected to come into the market with revolutionary properties in the next decade or so. They still need to be refrigerated, but using liquid nitrogen as a coolant is not too expensive. Condensing the most abundant gas in the air is as cheap as milk.
“Whilst being room temperature would be fantastic because there's no cooling needed, actually, to get to the temperatures we need to use the materials we've already got is pretty cheap and pretty easy,” Professor Speller explained to IFLScience.
There is a lot that scientists don’t know about how superconductivity emerges in a material and for this reason, it is difficult to find a material that is superconducting at room temperature and ambient pressure. The work goes on.