3 ms·

> Most high-temp superconductors (including LK-99, he was assuming it was one, since he's not qualified to say one way or the other) are a ceramic. The ones tha

> Most high-temp superconductors (including LK-99, he was assuming it was one, since he's not qualified to say one way or the other) are a ceramic. The ones that see use in the LHC, for instance, aren't. Aren’t the LHC magnets niobium-titanium? Those aren’t high temperature superconductors. Though it is indeed a metal under any definition. The rule of thumb is that high-temperature superconductors can be cooled by liquid nitrogen alone. This is not the case of the LHC magnets, which also have a liquid helium cooling loop. > They're metallic, so you can form them into the shape you need without having to manufacture it in that shape to begin with, since you'd need another superconductor to join pieces like glue, which we don't have. The term “metallic” is unhelpful because often in material science it just means an electronic conductor (a material with a non-zero density of states at the Fermi level). Under that definition, some ceramics are metallic, and the opposite of “metallic” is “insulator”, or sometimes “semi-conductor”. YBCO, which is probably the most used high-temperature superconductor, is an oxyde, so a ceramic, but still an electronic (super)conductor, so metallic. The fact that it’s an oxyde does not prevent its use, notably in spherical tokamaks. So I don’t know the person you’re referencing but their background work on the subject seems less than adequate, from what you say.

putnambr 3y ago
Did you skip over "In almost all applications of superconductors, they don't use high-temperature ones for one simple reason: Material properties." They're saying that LHC does not use a ceramic, and therefore high-temperature, superconductor; instead they use metallic (cooled) superconductors because they can be molded.
- kergonath 3y ago
  The sentence still does not make sense because the superconductors in the LHC (though, rereading it a couple of times it is somewhat ambiguous) are not high temperature by any definition. Also, again, ceramic high-temperature superconductors are metallic, or they would not be conductors. “Ceramic” and “metallic” are not mutually exclusive in material sciences. There are lots of reasons to use more classical superconductors in the LHC, just as in ITER. Some are design and engineering issues, as you mention. Another one is that the tapes we use for YBCO were not a practical thing when the LHC was designed. But now they are (though they haven’t been used in such a large scale) and you can bet that they’ll jump at any opportunity to get rid of the helium loop and take advantage of the stronger magnetic fields you can get with YBCO.
  - penjelly 3y ago
    can you make wires from cermets? Thats the point. we need a substance that is malleable(?) enough like copper wire that electrons can pass through. Pottery ceramic wont work like that.
    - kergonath 3y ago
      > can you make wires from cermets? Well, nobody mentioned cermets, or wires, and there are plenty of applications for superconductors beyond wires. Even so, we are perfectly able to make fibre optics cables with silica, which is a ceramic. > we need a substance that is malleable(?) enough like copper wire that electrons can pass through. Malleability (actually, ductility) has nothing to do with electric conductivity. It can be useful depending on the use case, but for example on a printed circuit you don’t care about that. Not everything is a dangling wire. YBCO a ceramic superconductor, it is used in thin films that are deposited on metallic substrates in tapes and it works well. See figure 2 of the paper here: https://www.researchgate.net/publication/271637455_Dipole_Magnet_from_High_Tc_Superconductor https://www.researchgate.net/publication/271637455_Dipole_Ma... . Also, you might not realise this but pretty much nothing is malleable at liquid helium temperature. > Pottery ceramic wont work like that. Sigh. Ceramics are not pottery, and more than 99% of the time do not have anything to do with pottery. Ceramics are compounds that are not intermetallic, typically oxides, sulphides, nitrides, etc. Some are bendy (though generally less than metallic alloys), some are hard, some are electric conductors, some are not. They have very diverse sets of properties. They are everywhere in the chips on the device you use, in its display, in the power plants that make electrons move so you can use it, in any lithium-ion battery, etc. I don’t think I can name one device that does not involve ceramics. Even a shovel, either in the form of a passive layer that makes it stainless, or in the form of rust on it. None of that has anything to do with pottery.
      - jacquesm 3y ago
        I think this misconception stems from people thinking 'earthenware' or 'clay' when they hear 'ceramics'.
    - 3y ago
spiznnx 3y ago
you are (mostly) agreeing (except for precise definitions of metallic and ceramic). Their comment is unclear, but it means "In almost all applications of superconductors, they don't use high-temperature ones. [...] The ones [the superconductors] that see use in the LHC, for instance, aren't [high temperature superconductors]." It just has a sentence in the middle of it that confuses you into thinking their antecedents are "the HTSCs" and "ceramic" instead of "the SCs" and "HTSCs".

putnambr 3y ago

Did you skip over "In almost all applications of superconductors, they don't use high-temperature ones for one simple reason: Material properties." They're saying that LHC does not use a ceramic, and therefore high-temperature, superconductor; instead they use metallic (cooled) superconductors because they can be molded.

kergonath 3y ago
The sentence still does not make sense because the superconductors in the LHC (though, rereading it a couple of times it is somewhat ambiguous) are not high temperature by any definition. Also, again, ceramic high-temperature superconductors are metallic, or they would not be conductors. “Ceramic” and “metallic” are not mutually exclusive in material sciences. There are lots of reasons to use more classical superconductors in the LHC, just as in ITER. Some are design and engineering issues, as you mention. Another one is that the tapes we use for YBCO were not a practical thing when the LHC was designed. But now they are (though they haven’t been used in such a large scale) and you can bet that they’ll jump at any opportunity to get rid of the helium loop and take advantage of the stronger magnetic fields you can get with YBCO.
- penjelly 3y ago
  can you make wires from cermets? Thats the point. we need a substance that is malleable(?) enough like copper wire that electrons can pass through. Pottery ceramic wont work like that.
  - kergonath 3y ago
    > can you make wires from cermets? Well, nobody mentioned cermets, or wires, and there are plenty of applications for superconductors beyond wires. Even so, we are perfectly able to make fibre optics cables with silica, which is a ceramic. > we need a substance that is malleable(?) enough like copper wire that electrons can pass through. Malleability (actually, ductility) has nothing to do with electric conductivity. It can be useful depending on the use case, but for example on a printed circuit you don’t care about that. Not everything is a dangling wire. YBCO a ceramic superconductor, it is used in thin films that are deposited on metallic substrates in tapes and it works well. See figure 2 of the paper here: https://www.researchgate.net/publication/271637455_Dipole_Magnet_from_High_Tc_Superconductor https://www.researchgate.net/publication/271637455_Dipole_Ma... . Also, you might not realise this but pretty much nothing is malleable at liquid helium temperature. > Pottery ceramic wont work like that. Sigh. Ceramics are not pottery, and more than 99% of the time do not have anything to do with pottery. Ceramics are compounds that are not intermetallic, typically oxides, sulphides, nitrides, etc. Some are bendy (though generally less than metallic alloys), some are hard, some are electric conductors, some are not. They have very diverse sets of properties. They are everywhere in the chips on the device you use, in its display, in the power plants that make electrons move so you can use it, in any lithium-ion battery, etc. I don’t think I can name one device that does not involve ceramics. Even a shovel, either in the form of a passive layer that makes it stainless, or in the form of rust on it. None of that has anything to do with pottery.
    - jacquesm 3y ago
      I think this misconception stems from people thinking 'earthenware' or 'clay' when they hear 'ceramics'.
  - 3y ago

spiznnx 3y ago

you are (mostly) agreeing (except for precise definitions of metallic and ceramic). Their comment is unclear, but it means "In almost all applications of superconductors, they don't use high-temperature ones. [...] The ones [the superconductors] that see use in the LHC, for instance, aren't [high temperature superconductors]." It just has a sentence in the middle of it that confuses you into thinking their antecedents are "the HTSCs" and "ceramic" instead of "the SCs" and "HTSCs".