https://arxiv.org/abs/2308.01723
>In fact, I find that Cu on this Pb(2) is 1.08 eV more energetically favorable than Cu on the Pb(1) site, suggesting possible difficulties in robustly obtaining Cu substituted on the Pb(1) site.
https://arxiv.org/abs/2307.16892
The paper from Dr. Griffin at LBNL suggests copper atoms have to be placed in a specific (but less likely) position in the molecule to result in the desired flat band characteristic. Also, the original authors and the labs who were able to replicate LK-99 are reporting they had to make multiple batches to even find a tiny piece that shows levitation. This suggests that you just have to be very lucky to produce a sample with high enough concentration of LK-99 to observe levitation.
If we can somehow confirm that LK-99 is truly a room temperature superconductor, billions of dollars of R&D fund will pour in to improve the fabrication process. When the first transistor was invented, people probably weren't imagining that we'll be mass producing them in nanometer scale in the future. Or maybe LK-99 will be stuck in a lab like graphene. Who knows?
