3 ms·

Doesn't it seem like there should be some sort of annealing process required? this material being essentially a powder smashed into a tablet form seems like it

by xt00 3y ago

Doesn't it seem like there should be some sort of annealing process required? this material being essentially a powder smashed into a tablet form seems like it would likely be a very poor conductor unless the superconducting properties not only existed in each of the granules of the powder, but also can easily transition between each of the boundaries. So wouldn't you want the final thing to be closer to like a ceramic form? (probably not understanding something here)

techdragon 3y ago
Unequivocally yes… which is why I wasn’t surprised when the first publicised reproduction involved a tiny grain, why the big pressed pellets seem to be staying put, why people are suggesting breaking the samples up, and why the original pictures/video showing the levitation that kicked all this off, is an oddly shaped sample that sort of looks like it flaked off a larger piece. Smash the samples… see if any of the grains float… (it’s becoming a bit of a refrain on Twitter whenever a big chunky pressed pellet sample is published as a failed replication) … it won’t be hard to improve the process and try and get larger contiguous samples that show the effect once we know for sure that it’s actually happening even if it’s happening in smaller more obviously superconducting samples, be it the size of a sand grain or a grain of rice, as long as it’s clearly a room temperature superconductor… once we have more samples… the analysis experts can get stuck in, there’s a global army of analytical experts… crystallographers, spectrographers, and all the sub disciplines of analytical chemistry… with clearly superconducting samples these people can swing into action and work out what the magic is and what we have to do to make more and bigger floating rocks.
- ethbr0 3y ago
  It'll be fascinating if an industrial production process involved grinding it up, using magnets as a screen to discard non-levitating particles, then reforming the compliant ones.
distortionfield 3y ago
The lack of annealing seems really problematic to me
- smaddox 3y ago
  If the DFT paper is correct, then annealing would let the Cu atoms relax to the Pb(2) sites, which doesn't induce potentially superconducting bands. Metastable alloys (roughly, alloys that are only stable at room temperature because the atoms get frozen in place too quickly for them to reach the energetically favorable positions) are quite common in materials science, both for bulk metals and for semiconducting crystals. There are far more possible metastable alloys than stable alloys, so the range of material properties possible in metastable alloys is far wider than that in stable alloys. So, considering we have never discovered a room temperature superconductor, so far, it wouldn't be particularly surprising if it requires a metastable alloy.
SkyPuncher 3y ago
I'm completely out of my league here. I was looking at the floating sample picture and it struck me as odd how the material levitates at an angle. [0] The broken part floating and the "pressed" part resting on the plate. To me, this suggests that a significant amount of the material is not the target material. Further, if the target material was evenly distributed, I'd expect that levitation properties would correlate with the thickness of the piece and the piece would float, evenly. Right, if a 1mm piece has 1unit of levitation, a 5mm piece should have 5 units of levitation. If the 1mm piece levitates, then the 5mm portion should as well. Since it's not levitating evenly, I suspect the target material is unevenly distributed. Further, I'd argue that the target material is actually consolidated to a single piece of that sample. Perhaps (conjecture) that little silver spec near the tip of the crack. From what I've been reading, it seems like it's very, very hard to trick the copper into the right place. It seems possible that the process does work, but a lot of luck is needed to create a large enough piece to support the levitation effect. It's almost like someone stuck a "super strong" helium balloon in the center of a half-eaten cake. The helium balloon lifts the cake, but the weight of the uneaten half of the cake causes tilt. 0 - https://www.newscientist.com/article/2384782-room-temperature-superconductor-breakthrough-met-with-scepticism/ https://www.newscientist.com/article/2384782-room-temperatur...
- rvnx 3y ago
  To prove that point, shouldn't they cut the material in half ? and keep only the levitating part ? Why haven't they done so ?
  - SkyPuncher 3y ago
    There's a lot of reasons, mainly that's a 1-way door type of situation.

by xt00 3y ago

techdragon 3y ago

Unequivocally yes… which is why I wasn’t surprised when the first publicised reproduction involved a tiny grain, why the big pressed pellets seem to be staying put, why people are suggesting breaking the samples up, and why the original pictures/video showing the levitation that kicked all this off, is an oddly shaped sample that sort of looks like it flaked off a larger piece. Smash the samples… see if any of the grains float… (it’s becoming a bit of a refrain on Twitter whenever a big chunky pressed pellet sample is published as a failed replication) … it won’t be hard to improve the process and try and get larger contiguous samples that show the effect once we know for sure that it’s actually happening even if it’s happening in smaller more obviously superconducting samples, be it the size of a sand grain or a grain of rice, as long as it’s clearly a room temperature superconductor… once we have more samples… the analysis experts can get stuck in, there’s a global army of analytical experts… crystallographers, spectrographers, and all the sub disciplines of analytical chemistry… with clearly superconducting samples these people can swing into action and work out what the magic is and what we have to do to make more and bigger floating rocks.

ethbr0 3y ago
It'll be fascinating if an industrial production process involved grinding it up, using magnets as a screen to discard non-levitating particles, then reforming the compliant ones.

distortionfield 3y ago

The lack of annealing seems really problematic to me

smaddox 3y ago
If the DFT paper is correct, then annealing would let the Cu atoms relax to the Pb(2) sites, which doesn't induce potentially superconducting bands. Metastable alloys (roughly, alloys that are only stable at room temperature because the atoms get frozen in place too quickly for them to reach the energetically favorable positions) are quite common in materials science, both for bulk metals and for semiconducting crystals. There are far more possible metastable alloys than stable alloys, so the range of material properties possible in metastable alloys is far wider than that in stable alloys. So, considering we have never discovered a room temperature superconductor, so far, it wouldn't be particularly surprising if it requires a metastable alloy.

SkyPuncher 3y ago

I'm completely out of my league here. I was looking at the floating sample picture and it struck me as odd how the material levitates at an angle. [0] The broken part floating and the "pressed" part resting on the plate. To me, this suggests that a significant amount of the material is not the target material. Further, if the target material was evenly distributed, I'd expect that levitation properties would correlate with the thickness of the piece and the piece would float, evenly. Right, if a 1mm piece has 1unit of levitation, a 5mm piece should have 5 units of levitation. If the 1mm piece levitates, then the 5mm portion should as well. Since it's not levitating evenly, I suspect the target material is unevenly distributed. Further, I'd argue that the target material is actually consolidated to a single piece of that sample. Perhaps (conjecture) that little silver spec near the tip of the crack. From what I've been reading, it seems like it's very, very hard to trick the copper into the right place. It seems possible that the process does work, but a lot of luck is needed to create a large enough piece to support the levitation effect. It's almost like someone stuck a "super strong" helium balloon in the center of a half-eaten cake. The helium balloon lifts the cake, but the weight of the uneaten half of the cake causes tilt. 0 - https://www.newscientist.com/article/2384782-room-temperature-superconductor-breakthrough-met-with-scepticism/ https://www.newscientist.com/article/2384782-room-temperatur...

rvnx 3y ago
To prove that point, shouldn't they cut the material in half ? and keep only the levitating part ? Why haven't they done so ?
- SkyPuncher 3y ago
  There's a lot of reasons, mainly that's a 1-way door type of situation.