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LK-99: Team of Southeast University observed zero resistance below 110 K

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Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#111

Post by floxy »

sema2 wrote: post #102
bigmattystyles wrote: post #75

Novice question - does a material behaving as a superconductor occur all the sudden like a step function if resistance is plotted against temp and pressure - or does it ease into super conductor behavior? (edit) Also is it resistance (aka if I remember my EE degree correctly), DC only or also impedance where frequency also matters?

I do find that interesting... I found a graph of another HTSC's (YBCO) resistance vs temperature [1], and the function is much more discontinuous looking than the one shown in the article. That would lead me (someone not at all trained in the physics of superconductors) to believe that perhaps the purity of the sample is a factor here, with different parts of the sample having different critical temperatures, gradual…

The ResearchGate chart has a linearly scaled y-axis, the Southeast University chart has a logarithmic scaled y-axis.

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#112

Post by piyh »

BasedAnon wrote: post #42
fgeahfeaha wrote: post #15

That's a failed repro then right? Below 110K is below -163.15 Celcius How would that compare to other superconductors?

technically a failure, but still a strange result

I don't think it's a failure if the original claims are showing some kind of promise, science is being done, and the frontiers of knowledge are being pushed forward.

In other words, not "Eureka!" but "that's weird".

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#113

Post by matsemann »

hcks wrote: post #100
omgJustTest wrote: post #41

This appears to be a great result. "Room temperature" super conductor result? No. But this is basically showing there is some superconductivity in the sample, and cooler temperatures expose intrinsic band structures. Pretty exciting!

How is it exciting? It invalidates the original claim. We already have better SC.

It doesn't invalidate the original claim, as they haven't been able to make a pure sample to test with, as I understand it. Or at least that there is some difference between their samples and the others, but still it shows promise.

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#115

Post by adolph »

jacquesm wrote: post #26
gchadwick wrote: post #14

Certainly no expert here but if you take the original video and replications at face value it does exhibit strong diamagnetism at room temperature. Superconductors are diamagnetic due to the Meissner effect at their superconducting temperature. This would mean LK99 is a superconductor at low temperature and separately be strongly diamagnetic at room temperature (no Meissner effect if it's not super conducting). Would…

It's all unusual because it is uncharted territory. My guess would be assuming that it all pans out that this is due to various impurities and that it will take a while before we have a sample that is pure enough that all of these properties can be nailed down for good. What's strange is that drop at higher temps, that's either a measurement anomaly or something really odd.

> due to various impurities and that it will take a while before we have a sample that is pure enough that all of these properties can be nailed down for good.

Do you think it will be "purity" or understanding material variance/specific impurity?

It reminds me of Fogbank, the nuke material claimed to be "so secret they forgot how to make it." Part of the story of manufacturing difficulty was due to increased purity of modern materials/processes.

In a bizarre twist, the new production facility and reverse-engineered production process yielded a version of Fogbank that was of a higher purity than it had been in the past, according to the article. The problem, however, was that for Fogbank to work as intended in existing warhead designs, that previous level of impurity was actually essential. NNSA had to revise the process to ensure the final product was just as impure.

https://www.thedrive.com/the-war-zone/32867/fogbank-is-myste...

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#116

Post by jacquesm »

borkt wrote: post #107
jacquesm wrote: post #93

Earlier quoted context omitted.

Yes, that's true, but that would require a shift in our understanding of physics and everything about this saga so far has not done that. And that in part is a reason why people take this serious: it is believable. New physics would raise the bar considerably. So for now I'm on the measuring error, impurity or process issue side of that without committing to which team I think has the problematic side.

The fact that our existing computational models are in agreement with the experimental behavior leads me to believe there is no new physics involved here. That being said this raises the question as to whether this class of material is known and characterized within our national research labs but has been kept classified, and if it was unknown it raises the question of why experimentation is what discovered it and wh…

> why we [we]ren't we able to harness the computational model to identify it theoretically and develop a method to produce it practically prior to this.

Because the computational requirements are off the scale in the most literal sense. The search space is so large that you won't be able to come up with an improvement in efficiency for your search unless you guide it very carefully with experimentally obtained results and that's exactly what these people were doing as far as I understand it. You mix up a batch of stuff, test it for gross properties, do crystallography and then use the information from that to do some numerical simulations to check if your assumptions and observations hold up.

I don't think we had this compound before.

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#117

Post by ceejayoz »

NickM wrote: post #72
meindnoch wrote: post #30

Earlier quoted context omitted.

Start shorting power companies.

Hypothetically, if we did end up with a worldwide superconducting energy grid, this would smooth load, which I would expect would make generation cheaper (since we can get rid of the need for expensive peaker plants and/or stationary storage requirements to handle local demand spikes). This would therefore make power companies more profitable, no?

Probably depends on the power company.

The ones with a lot of coal plans would suffer; the ones with a bunch of solar/wind farms in prime locations that can dramatically expand capacity (think things like giant solar farms in the Australian outback) would benefit.

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#118

Post by floxy »

hatsunearu wrote: post #103

The Fig 3a)b) graphs are not showing superconductivity. That just looks like the resistance dips below the ~1e-5 mark and goes goes deep into the noise. That just looks like a normal conductor that has a positive temperature coefficient. edit: to add speculation, I think they made something that's not quite LK-99, and it's behaving like a normal conductor with no superconductance.

An excitation of 1mA and R = 1e-5 means the voltage is 10 nV (1e-8). Also the chart has a logarithmic y-axis.

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#119

Post by Palpatineli »

matsemann wrote: post #113
hcks wrote: post #100

Earlier quoted context omitted.

How is it exciting? It invalidates the original claim. We already have better SC.

It doesn't invalidate the original claim, as they haven't been able to make a pure sample to test with, as I understand it. Or at least that there is some difference between their samples and the others, but still it shows promise.

[flagged]

Re: LK-99: Team of Southeast University observed zero resistance below 110 K

#120

Post by jacquesm »

adolph wrote: post #115
jacquesm wrote: post #26

Earlier quoted context omitted.

It's all unusual because it is uncharted territory. My guess would be assuming that it all pans out that this is due to various impurities and that it will take a while before we have a sample that is pure enough that all of these properties can be nailed down for good. What's strange is that drop at higher temps, that's either a measurement anomaly or something really odd.

> due to various impurities and that it will take a while before we have a sample that is pure enough that all of these properties can be nailed down for good. Do you think it will be "purity" or understanding material variance/specific impurity? It reminds me of Fogbank, the nuke material claimed to be "so secret they forgot how to make it." Part of the story of manufacturing difficulty was due to increased purity o…

> Do you think it will be "purity" or understanding material variance/specific impurity?

It could be either.

As I pointed out in other comments, that's how radioactivity was discovered and it is very well possible that they blundered into something exceptional by accident, it is also possible that both parties got it wrong and there are yet other effects at play (see the big gap in the t/R curve, that really needs explaining).

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