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LK-99 is a quasi two-dimensional material, and one which seems particularly challenging to synthesize in a bulk polycrystalline three-dimensional mass. Even th

LK-99 is a quasi two-dimensional material, and one which seems particularly challenging to synthesize in a bulk polycrystalline three-dimensional mass. Even the original researchers stated that they'd "get it right" only a fraction of the time, and that their famous floating cracked-disc is still impure. I think that there's no reason to assume that negative results right now are conclusive, whereas positive results are strongly indicative.

ThePhysicist 3y ago
It's a hexagonal lead-apatite crystal, how is that "quasi two-dimensional"?
- jstanley 3y ago
  I don't know anything about lead-apatite crystals, but I know that hexagons are 2-dimensional.
  - kergonath 3y ago
    Hexagonal refers to the type of crystal lattice. Most hexagonal crystals, including apatites, have a 3-dimensional structure.
- A_D_E_P_T 3y ago
  Even lead apatite is anisotropic. It conducts electrons along a plane from lead atom to lead atom --- where the phosporous atoms are insulators. Superconductivity in LK-99 moves along a similarly anisotropic two-dimensional plane.
  - ThePhysicist 3y ago
    Do you have a reference for that claim?
kergonath 3y ago
> LK-99 is a quasi two-dimensional material There is nothing 2-dimensional about the Apatite structure, and the preprints I have seen do not show any kind of “quasi two-dimensional” structure. If anything, it’s more like an array of tubes and chains, more 1D than 2D. Do you have a source making this claim?
- cubefox 3y ago
  1D would arguably make it even more challenging to synthesize than 2D.
  - kergonath 3y ago
    Not really. It’s more of a matter of chemistry and bonding than the dimensionality of the structure.
    - cubefox 3y ago
      I think the lower the dimensionality, the harder it is to align pieces. For 3D material you could probably just grind your impure sample down into a powder, isolate the grains that levitate, and press them back together. That wouldn't preserve structures in 2D though, let alone 1D.
      - kergonath 3y ago
        > I think the lower the dimensionality, the harder it is to align pieces. First, you’re not talking about synthesis anymore. And if you try to grow a single crystal, how easy it is to get polycrystals from powder is not really relevant. Ease to synthesise and ease to assemble are very different things and both are controlled by different phenomena. Also, again, not really. Graphene is quasi 2-dimensional and very easy to bunch up and form graphite, for example. Boron nitride, not that much. > For 3D material you could probably just grind your impure sample down into a powder, isolate the grains that levitate, and press them back together. You can do something like that (hot or cold pressing), but it still requires the right material to be synthesised in the first place. It works more or less well depending on chemistry and physical properties, not dimensionality. Separating “grains that work” and “grains that don’t” is not something we really do when we create materials. It sounds more like QA in semiconductors than something we’d do in a lab. > That wouldn't preserve structures in 2D though, let alone 1D. Why not? If you grind a 2-D structure joint you just get flat grains. How well they assemble depends on their properties. The whole discussion is not very productive: however truthy it sounds, dimensionality does not control how easy it is to synthesise a material. Apatites are very easy to make. Things like chalcogenide glasses are easy to make despite having a 1-dimensional structure at the atomic scale. There are many other examples. And, also again: it does not matter because apatites are fully 3-d structures, with linear elements if you squint and ignore how these elements are placed in the overall structure.
samwillis 3y ago
> seems particularly challenging to synthesize My reading of the situation was that they have been making this stuff for quite a while (years!), but haven't had the funding or manufacturing expertise to start scaling up and properly improving the process. They are a tiny research lab. The suggestion seems to be that one newer (now former) member of the lab just thought F-this we need to publish, get it out there and start moving forward. If it is real, the level of investment in finding ways to make this stuff is going to explode. It may be hard to make, but that won't stop us from finding a way to make it on a large scale if it truly is revolutionary. Further to that, from other groups studying it we will potentially find better and easer to make alternatives.
- jiggawatts 3y ago
  > quite a while (years!) Katalin Karikó was working on mRNA vaccine technology for decades on a relatively tiny budget, and was turned down by many larger groups based on the supposed impossibility of the concept. You have to wonder how many future technologies are languishing right now in some basement lab where a couple of frustrated scientists are making do with a shoestring budget and are desperate to get their research published.
- N-Krause 3y ago
  Where did you get that "(years!)" from? Is it just a conclusion you came to or are those actual facts. If so, I would love to see a source or a direction to where to look for it.
  - fallingknife 3y ago
    The 99 in lk99 means 1999
  - conception 3y ago
    https://en.m.wikipedia.org/wiki/LK-99 https://en.m.wikipedia.org/wiki/LK-99 It’s called LK-99 as it was discovered in 1999.
  - samwillis 3y ago
marcosdumay 3y ago
I'd say that positive results are only strongly indicative if they contain some property that absolutely can not be explained any other way (like the full levitation of that badly sourced video that we can't be sure abut the veracity) or if they are numerous enough to rule out rare effects. Outside of that, positive results only weakly imply LK-99 is real.
fguerraz 3y ago
I have my I WANT TO BELIEVE poster ready
jona-f 3y ago
Doesnt LK-99 crystallize in the perovskite structure? That's very 3D. I think cuprate superconductors do too, but I'm guessing, cause it's a long time I was into that sort of thing. What do you mean by "quasi two-dimensional". Every crystal has 2d planes (apart from rare penrose-style quasicrystals) and many crystals are anisotropic. People don't call these "quasi two-dimensional" afaik.
Qwertious 3y ago
>LK-99 is a quasi two-dimensional material, Hey, what does this actually mean? Like, space is 3D and I don't think you're claiming all LK99 samples are all literally-one-atom-thick, so clearly it's a 3D object. I'd guess it means that the material has very regular layers, but (much like graphene) I've never actually seen someone directly say what "two-dimensional material" means 3-dimensionally.
- DiscoBahb 3y ago
  Think of it this way: in something like copper, atoms are arranged in a 3d lattice, and electrons are able to jump (or "tunnel") from copper atom to copper atom freely in any of the x, y or z directions because the lattice looks the same in each direction. Some more complex materials do not have this symmetry, and the ability of the electrons to tunnel is much stronger in some directions than others. In many known high temperature superconductors electrons are more or less confined to move in a 2d plane (even though a lump of the material is obviously a 3d object) so they are called "quasi-2d". In other materials they are confined to move in only one direction, which seems to be the case with LK-99
lost_tourist 3y ago
"...whereas positive results are strongly indicative..." [if the claims come from highly respected labs with experienced experimental scientists]

ThePhysicist 3y ago

It's a hexagonal lead-apatite crystal, how is that "quasi two-dimensional"?

jstanley 3y ago
I don't know anything about lead-apatite crystals, but I know that hexagons are 2-dimensional.
- kergonath 3y ago
  Hexagonal refers to the type of crystal lattice. Most hexagonal crystals, including apatites, have a 3-dimensional structure.
A_D_E_P_T 3y ago
Even lead apatite is anisotropic. It conducts electrons along a plane from lead atom to lead atom --- where the phosporous atoms are insulators. Superconductivity in LK-99 moves along a similarly anisotropic two-dimensional plane.
- ThePhysicist 3y ago
  Do you have a reference for that claim?

kergonath 3y ago

> LK-99 is a quasi two-dimensional material There is nothing 2-dimensional about the Apatite structure, and the preprints I have seen do not show any kind of “quasi two-dimensional” structure. If anything, it’s more like an array of tubes and chains, more 1D than 2D. Do you have a source making this claim?

cubefox 3y ago
1D would arguably make it even more challenging to synthesize than 2D.
- kergonath 3y ago
  Not really. It’s more of a matter of chemistry and bonding than the dimensionality of the structure.
  - cubefox 3y ago
    I think the lower the dimensionality, the harder it is to align pieces. For 3D material you could probably just grind your impure sample down into a powder, isolate the grains that levitate, and press them back together. That wouldn't preserve structures in 2D though, let alone 1D.
    - kergonath 3y ago
      > I think the lower the dimensionality, the harder it is to align pieces. First, you’re not talking about synthesis anymore. And if you try to grow a single crystal, how easy it is to get polycrystals from powder is not really relevant. Ease to synthesise and ease to assemble are very different things and both are controlled by different phenomena. Also, again, not really. Graphene is quasi 2-dimensional and very easy to bunch up and form graphite, for example. Boron nitride, not that much. > For 3D material you could probably just grind your impure sample down into a powder, isolate the grains that levitate, and press them back together. You can do something like that (hot or cold pressing), but it still requires the right material to be synthesised in the first place. It works more or less well depending on chemistry and physical properties, not dimensionality. Separating “grains that work” and “grains that don’t” is not something we really do when we create materials. It sounds more like QA in semiconductors than something we’d do in a lab. > That wouldn't preserve structures in 2D though, let alone 1D. Why not? If you grind a 2-D structure joint you just get flat grains. How well they assemble depends on their properties. The whole discussion is not very productive: however truthy it sounds, dimensionality does not control how easy it is to synthesise a material. Apatites are very easy to make. Things like chalcogenide glasses are easy to make despite having a 1-dimensional structure at the atomic scale. There are many other examples. And, also again: it does not matter because apatites are fully 3-d structures, with linear elements if you squint and ignore how these elements are placed in the overall structure.

samwillis 3y ago

> seems particularly challenging to synthesize My reading of the situation was that they have been making this stuff for quite a while (years!), but haven't had the funding or manufacturing expertise to start scaling up and properly improving the process. They are a tiny research lab. The suggestion seems to be that one newer (now former) member of the lab just thought F-this we need to publish, get it out there and start moving forward. If it is real, the level of investment in finding ways to make this stuff is going to explode. It may be hard to make, but that won't stop us from finding a way to make it on a large scale if it truly is revolutionary. Further to that, from other groups studying it we will potentially find better and easer to make alternatives.

jiggawatts 3y ago
> quite a while (years!) Katalin Karikó was working on mRNA vaccine technology for decades on a relatively tiny budget, and was turned down by many larger groups based on the supposed impossibility of the concept. You have to wonder how many future technologies are languishing right now in some basement lab where a couple of frustrated scientists are making do with a shoestring budget and are desperate to get their research published.
N-Krause 3y ago
Where did you get that "(years!)" from? Is it just a conclusion you came to or are those actual facts. If so, I would love to see a source or a direction to where to look for it.
- fallingknife 3y ago
  The 99 in lk99 means 1999
- conception 3y ago
  https://en.m.wikipedia.org/wiki/LK-99 https://en.m.wikipedia.org/wiki/LK-99 It’s called LK-99 as it was discovered in 1999.
- samwillis 3y ago

marcosdumay 3y ago

I'd say that positive results are only strongly indicative if they contain some property that absolutely can not be explained any other way (like the full levitation of that badly sourced video that we can't be sure abut the veracity) or if they are numerous enough to rule out rare effects. Outside of that, positive results only weakly imply LK-99 is real.

fguerraz 3y ago

I have my I WANT TO BELIEVE poster ready

jona-f 3y ago

Doesnt LK-99 crystallize in the perovskite structure? That's very 3D. I think cuprate superconductors do too, but I'm guessing, cause it's a long time I was into that sort of thing. What do you mean by "quasi two-dimensional". Every crystal has 2d planes (apart from rare penrose-style quasicrystals) and many crystals are anisotropic. People don't call these "quasi two-dimensional" afaik.

Qwertious 3y ago

>LK-99 is a quasi two-dimensional material, Hey, what does this actually mean? Like, space is 3D and I don't think you're claiming all LK99 samples are all literally-one-atom-thick, so clearly it's a 3D object. I'd guess it means that the material has very regular layers, but (much like graphene) I've never actually seen someone directly say what "two-dimensional material" means 3-dimensionally.

DiscoBahb 3y ago
Think of it this way: in something like copper, atoms are arranged in a 3d lattice, and electrons are able to jump (or "tunnel") from copper atom to copper atom freely in any of the x, y or z directions because the lattice looks the same in each direction. Some more complex materials do not have this symmetry, and the ability of the electrons to tunnel is much stronger in some directions than others. In many known high temperature superconductors electrons are more or less confined to move in a 2d plane (even though a lump of the material is obviously a 3d object) so they are called "quasi-2d". In other materials they are confined to move in only one direction, which seems to be the case with LK-99

lost_tourist 3y ago

"...whereas positive results are strongly indicative..." [if the claims come from highly respected labs with experienced experimental scientists]