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Preprint by Griffin from Livermore Labs gives a theoretical explanation of LK-99's superconductivity and also explains why labs are having a hard time synthesiz
by jboggan 3y ago
Preprint by Griffin from Livermore Labs gives a theoretical explanation of LK-99's superconductivity and also explains why labs are having a hard time synthesizing it. There are two Pb sites in the crystal structure that Cu can substitute at, the lower energy one does nothing but it's the higher energy site that creates superconductivity.
https://arxiv.org/pdf/2307.16892.pdf https://arxiv.org/pdf/2307.16892.pdf
"Finally, the calculations presented here suggest that
Cu substitution on the appropriate (Pb(1)) site displays
many key characteristics for high-TC superconductivity,
namely a particularly flat isolated d-manifold, and the
potential presence of fluctuating magnetism, charge and
phonons. However, substitution on the other Pb(2) does
not appear to have such sought-after properties, despite
being the lower-energy substitution site. This result hints
to the synthesis challenge in obtaining Cu substituted on
the appropriate site for obtaining a bulk superconducting
sample."
- peteradio 3y agoWhat does this mean for synthesis? You just have to try a ton of times and get lucky? Is there some way to influence site substitution?
- syrgian 3y agoI'm guessing the diamagnetic property will make it easy to separate the successful bits from the unsuccessful ones at scale.
- jmartin2683 3y agoEngineer thinking, right there
- appplication 3y agoI was a chemistry major, but didn’t take it up as a career so I won’t pretend to be an expert. There are a lot of tools in the chemist’s cookbook for dealing with exactly this sort of problem. It doesn’t mean it’s easy, but experienced chemists will understand how to approach solving this.
- deleted 3y ago[deleted]
- sweezyjeezy 3y agoHave a friend who works in superconductivity and from what they say this is pretty standard - the way experimental superconductors are generally created is by spraying atoms onto a film over and over until you get one that works [< 10% success rate is common]. There are other ways to do it more reliably and in larger quantities once you have a confirmed superconductor, but they're also slower during the experimental stage.
- deleted 3y ago[deleted]
- 2bitencryption 3y agoQuestions from a total layman- Are the superconductivity properties "all or nothing"? Meaning, if you get the synthesis wrong of the material, would you expect it to be "kind of" superconductive? (I guess, a very low, but non-0, resistance)? Or is it something where it has normal resistance in all cases unless you get it just right, and then it becomes superconducting? One more question - in physics, it seems like something having a value "0" is never really possible. Like, you can have something with low friction, but not zero friction. We pretend things have zero friction for high school physics problems, but they don't really. Is superconductivity like that? Is it actually, genuinely, exactly 0.0000(...)? Or is it just very close to zero, so close that it can behave like something with zero resistance (but in reality it's resistive, but just barely)?
- sbierwagen 3y agoIt really is authentically zero. No resistance at all. The thing that prevent infinities showing up, or letting us pour gigawatts of power into a single superconducting magnet until it turns into a black hole is that superconductors have a "critical current" over which it falls out of the superconducting state. (At which point it enters the normal, resistive state, suddenly becomes very hot, and boils off all your very expensive liquid helium, a "magnet quench" https://en.wikipedia.org/wiki/Superconducting_magnet#Magnet_quench https://en.wikipedia.org/wiki/Superconducting_magnet#Magnet_... ) LK-99's published critical current is actually quite low, maybe because of sample purity issues. Hopefully it can be improved, otherwise we might be in the comical situation where room temperature superconductors exist and can be used but the cables end up being too thick and can't compete economically with copper.
- tetha 3y ago> LK-99's published critical current is actually quite low, maybe because of sample purity issues. Hopefully it can be improved, otherwise we might be in the comical situation where room temperature superconductors exist and can be used but the cables end up being too thick and can't compete economically with copper. This would btw be similar to a proof of P = NP, including the caveat that the best-case runtime of an NP-hard problem is a polynomial of degree 40000. It'd be polynomial runtime, but very much in the "ouch" and "infeasible" territory.