>Most likely, the material LK99 as reported in [1-3] is a heterophase structure, with co-existent non-superconducting constituents. This may yield superconducting droplets surrounded by nonsuperconducting material...
>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.
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?
From a purely scientific angle, so presumably less amenable to mass production, why doesn't anyone use FT-ICR mass spectrometers to assemble say a unit cell?
There is a good classic primer on FT-ICR, mostly focused on analysis (mass spectrometry) but also mentioning activation energies for reactions and measurement of kinetics etc.
If you dunk a bunch of chemicals (for simplicity think wet chemistry) in a vial, all reactions and side reactions are simultaneously occuring, so one has little control over what happens on an atomic scale.
FT-ICR can be used to observe the state AND to manipulate the state. Its like having a compact particle collider, but instead of the high (TeV) energy in CERN etc. its just chemical energy levels.
It happens in high vacuum, so low densities of species, hence not amenable to mass production.
But the instrument is both eyes and hands: one can identify the frequencies corresponding to each ionized molecule, and selectively energize or de-energize specific species to encourage or prevent main and competing reactions, by pumping or damping specific frequencies.
One may build up a molecule in elementary steps and eject finished molecules. Those steps can occur at the same time in the same vessel. Its like having a miniature digitally controlled chemical plant, without having to redo all the pipework if you decide to use a different pathway here or there.
The good news is that we should know within a few weeks if rock surgery is effective. If that works they can increase the purity and sample size without needing to find a new creation process
There are a ton of suggestions floating around already on how the efficiency could be improved and some of those are very clever and involve using the superconducting properties of the individual grains to help sort them out from the bulk material.
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?