5 ms·

I'm still unclear. Why is the test limit 110K? If this is supposed to be usable at ambient temperature then this seems like not a useful finding. Is it just som

by tootie 3y ago

I'm still unclear. Why is the test limit 110K? If this is supposed to be usable at ambient temperature then this seems like not a useful finding. Is it just some artifact of how superconductivity is measured?

danielheath 3y ago
Some people say they can get it to work at room temperature, and others say they can't. Testing a sample at superconductivity-friendly temperatures helps figure out whether there's something to investigate here, since most materials do not superconduct at any useful temperature.
golol 3y ago
The common understanding seems to be that producing true LK99 is very difficult as you need to get the crystal structure just right. Many samples probably have mixes of the correct and other structures. That's why some float and some don't. The sample might be quite "dirty", meaning the critical temperature is lower.
- trafficante 3y ago
  Seems like it may depend on getting specific binding sites. > 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. [1] 1. https://arxiv.org/abs/2307.16892 https://arxiv.org/abs/2307.16892
valianteffort 3y ago
I believe 110K is where it hit zero resistivity (the lower bound) but any increase from there and it was no longer presenting superconductivity. If we are to trust the SK team, it's possible the design in the paper is outdated and in-house they have dialed it in to something stable at room temperature.
saberdancer 3y ago
Most materials are not superconductors at 110K. If this one is, it is possible Koreans did not fake room temperature results but rather their sample is slightly different for some reason, maybe pure luck, maybe some part of process that they didn't clearly define or that their precursor materials have certain impurities.
- deleted 3y ago
  [deleted]
- CitizenKane 3y ago
  It is apparently extremely difficult to fabricate LK-99 and most of the time the process being used creates similar substances but without appropriate Cu substitution in its lattice. All of the videos have been of generally quite small samples and the manufacturing difficulty is the purported reason. The SK also supposedly had more details on this but with the leak of the paper those haven't been cleaned up and added to the paper.
  - selestify 3y ago
    I thought the original hype around LK-99 was that it was supposed to be easy to manufacture with materials most labs have on hand? E.g. https://news.ycombinator.com/item?id=36865106 https://news.ycombinator.com/item?id=36865106
    - caturopath 3y ago
      - It was naive to think a simple recipe was going to play out with everyone getting what they wanted easily when they tried to follow it. - It's still a huge deal if the manufacturing is as easy as it appears to be, even if most of the replication attempts aren't getting _quite_ the right thing. It's hilarious if room temperature superconductors were always "Put these two things in a lucifer furnace and roll a die" away.
      - xyzzy_plugh 3y ago

by tootie 3y ago

danielheath 3y ago

Some people say they can get it to work at room temperature, and others say they can't. Testing a sample at superconductivity-friendly temperatures helps figure out whether there's something to investigate here, since most materials do not superconduct at any useful temperature.

golol 3y ago

The common understanding seems to be that producing true LK99 is very difficult as you need to get the crystal structure just right. Many samples probably have mixes of the correct and other structures. That's why some float and some don't. The sample might be quite "dirty", meaning the critical temperature is lower.

trafficante 3y ago
Seems like it may depend on getting specific binding sites. > 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. [1] 1. https://arxiv.org/abs/2307.16892 https://arxiv.org/abs/2307.16892

valianteffort 3y ago

I believe 110K is where it hit zero resistivity (the lower bound) but any increase from there and it was no longer presenting superconductivity. If we are to trust the SK team, it's possible the design in the paper is outdated and in-house they have dialed it in to something stable at room temperature.

saberdancer 3y ago

Most materials are not superconductors at 110K. If this one is, it is possible Koreans did not fake room temperature results but rather their sample is slightly different for some reason, maybe pure luck, maybe some part of process that they didn't clearly define or that their precursor materials have certain impurities.

deleted 3y ago
[deleted]
CitizenKane 3y ago
It is apparently extremely difficult to fabricate LK-99 and most of the time the process being used creates similar substances but without appropriate Cu substitution in its lattice. All of the videos have been of generally quite small samples and the manufacturing difficulty is the purported reason. The SK also supposedly had more details on this but with the leak of the paper those haven't been cleaned up and added to the paper.
- selestify 3y ago
  I thought the original hype around LK-99 was that it was supposed to be easy to manufacture with materials most labs have on hand? E.g. https://news.ycombinator.com/item?id=36865106 https://news.ycombinator.com/item?id=36865106
  - caturopath 3y ago
    - It was naive to think a simple recipe was going to play out with everyone getting what they wanted easily when they tried to follow it. - It's still a huge deal if the manufacturing is as easy as it appears to be, even if most of the replication attempts aren't getting _quite_ the right thing. It's hilarious if room temperature superconductors were always "Put these two things in a lucifer furnace and roll a die" away.
    - xyzzy_plugh 3y ago