3 ms·
I'm glad to hear that I'm not the only one who thought that the DFT computational preprints were very promising. Unfortunately, they also indicate that the des
by scythe 3y ago
I'm glad to hear that I'm not the only one who thought that the DFT computational preprints were very promising.
Unfortunately, they also indicate that the desired substitution will be very hard to achieve — crucially, the "crush and separate the composite" suggestion a few commenters have made is unlikely to work, since the heterogeneity exists within the same crystal, depending on whether Cu substitutes into Pb {1} (good) or Pb {2} (bad) crystal sites. This may be why the very oblique synthetic approach favored by the authors — reacting copper phosphide with lanarkite, giving lots of copper sulfide byproduct — was needed to give interesting properties. Now that we have an idea of what to look for, though, it may be possible to derive other synthetic approaches with a clear idea of what particular sort of copper substitution should be achieved, and a way to determine if it was achieved.
Of course, there remains a possibility that all of this is a big mistake, but now it would have to be several correlated mistakes. It may be a long time until the necessary selective substitution is achieved in a high-quality bulk sample, so, going on this hypothesis, I do not expect a sudden rush of new technologies in the near-term.
- gaze 3y agoKinda? You'd expect flat bands from putting a copper atom into a big insulating supercell. The population of the d band is interesting, though. I don't find it super super compelling, but it's certainly not nothing.
- radioactivist 3y agoYes, given the Cu atoms seem to be ~8 Angstrom apart the flat bands are to be expected. So its not clear what "special" about these, given if you just had dilute Cu impurities in some otherwise insulating I'd imagine you'd have something similar for the Cu d-bands.
- calf 3y agoCould there be limitations to making a large piece of this crystal, so in practice it is never useful?
- ironborn123 3y agoA question that arises, how good is chemical vapor deposition (albeit a very expensive way and hence for labwork only) in creating a pure sample with proper Cu substitutions?
- carabiner 3y agoThe widespread consensus among experts who have done DFT is that the preprint doesn't add anything to how they feel about LK-99. https://twitter.com/alexkaplan0/status/1686392015217741825 https://twitter.com/alexkaplan0/status/1686392015217741825 sums it up: Griffin's paper is neither proof of superconductivity nor even a very strong signal of it. Flat bands can mean many things; in fact, the crystal structure Griffin assumes may have been selected due to their likelihood. CMTC says the Griffin paper doesn't really shift anything and they still believe replication is unlikely: https://twitter.com/condensed_the/status/1686373904044949504?s=46&t=N5oP9SrFuyxd0pRLixzkBQ https://twitter.com/condensed_the/status/1686373904044949504...
- weard_beard 3y agoMaybe you can help here, I was completely lost in terms of the Iris (Russian Cat Girl) mention of, "engineering conductivity pili of bacteria into the superconductors" is this a reference to nano scale bio engineering or a means of reliable replication of the superconducting structure itself? Or is this just nonsense? https://twitter.com/iris_IGB/status/1685322871306928128 https://twitter.com/iris_IGB/status/1685322871306928128
- feoren 3y agoSounds like nonsense. You can't do atomic-level engineering with bacteria, they are 9 orders of magnitude too big. We're talking about being able to place copper atoms at specific points on a crystal structure, while avoiding placing them at points they'd rather be at. Bacteria? Give me a break.