It has all the hallmarks of something very much rushed into publication: misspelled words, awkward phrasing, out-of-order paragraphs, misnumbered figures, and (most charmingly) error messages in Korean from their bibliography software. At this stage of things, all that is understandable and excusable.
A few things are presented in a peculiar way, unlike most of the other sc papers I’ve read. Again, that’s more or less ok once you disentangle the coordinate systems on the plots and the like. It can be fixed easily, and probably will be.
To convince anybody to take you seriously enough to test for superconductivity, you have to demonstrate 4 things: (1) 0 resistivity below a reasonably sharply defined temperature, (2) the existence of a critical current above which transition back to normal occurs, (3) the existence of a similary critical magnetic field, and (4) the Meissner effect, or magnetic flux expulsion (totally for Type I and at least partially for Type II).
They did the first 3 of those reasonably believably (even to a guy like me who still has scars from the cold fusion mishegoss back in the day). The Meissner effect, though, gets only partial credit: the diamagentism for the field-cooled & non-field-cooled samples implies an unphysical value of the diagmagentism, and the picture/video of a sample on a magnet only sorta-partially levitates.
The diamagnetism curve has apparently been addressed, as the authors say it was simply a copy-paste error on the graph. The Meissner effect visuals could be explained by the fact that they have a polycrystalline sample (resistance between domain boundaries) of unknown impurities (sometimes coppuer sulfides, other times the Pb/Cu doping may vary across the sample). (Again, this is totally excusable given the rush.) When other people start preparing samples, we’ll see what’s happening here.
It’s not going to revolutionize anything in its current early form:
(1) Frankly, it looks like charcoal. It’s almost certainly not ductile enough to form a wire, and any long thin sample that looks like a wire would be too brittle to wind into a coil.
(2) The critical magnetic field is pretty low, maybe 0.3 Tesla at room temp. For comparison, the tokamak magnets being used by Commonwealth Fusion Systems for their prototype reactors weigh in at 20 Tesla.
(3) The critical current is low. The right thing is to report a current density, but they only report total current without information on sample shape. Still, they topped out at around 250 mA. For comparison, the CFS tokamak magnets run around 40 kA.
IF IT REPLICATES, it’s a fascinating step in phyics (mechanism proposes stressed crystals forming an array of superconducting quantum wells, with currents forming by electron tunneling along the Pb metal backbone… maybe).
But as it is, it’s not an engineering material.
THAT IS ABSOLUTELY OK! This is an early stage compound, all it has to demonstrate that it works. Then tons of material scientists and physicists will start tweaking the recipe, to optimize transition temperature, critical current, and critical field.
Also, I hope, somebody will figure out how use something other than lead. Right now it doesn’t use rare earths, which is good. But it would be better if we could use something with a similar crystal structure to the lead apatite (Lanarkite), but less toxicity.
Then last night all hell broke loose. Kwon made a conference presentation. During that, Lee and the other authors more or less disowned him, said he was fired from the university and the company, and that the first paper was an unauthorized upload by Kwon. Then they retracted the first paper that Kwon apparently wrote on his own and uploaded.
Drama drama drama.
I’m waiting for Argonne, which seems to be on deck for a replication trial next week.
Absolutely! It’s not ductile enough for wire, and too frangible to bend around a coil even if you managed to make a long thin piece.
But… the early high-Tc superconductors in the 80s were ceramics, too. Even now, with much more friendly materials, the “wire” in the Commonwealth Fusion Systems tokamak prototype is actually a complex tape with multiple layers mostly for structural support.
Here’s a very nice, more technical presnentation at Princeton by a CFS person, showing the tape strucdture, and how the material had to evolve from microcrystalline stuff to much more complex forms to be useful in an engineering sense:
https://suli.pppl.gov/2020/course/20200619_SULI_HTS_Sorbom_Final.pdf
Also note: fusion-relevant REBCO magnets operate at 20T fields and 40kA currents, whereas this new superconductor can’t get above 0.3T fields and 250mA current. Lots of work to do there!
So I hope that gives the right idea: getting from today’s charcoal lump/floaty rock to something with optimized chemistry, easier manufacturability, ductility close enough to wire, and deployable in high fields & high currents took about 30 years the last time it was done.
It’ll be quicker this time, getting from the current charcoal to whatever works, because the incentives are higher. But it almost certainly won’t be simpler.
(Variant of something I put as a comment on Zvi’s blog.)
Yesterday I put up a blog post that walks through the 2 papers on LK-99 superconductivity in the style of what in grad school they call “Journal Club”: https://www.someweekendreading.blog/high-tc-sc/
It has all the hallmarks of something very much rushed into publication: misspelled words, awkward phrasing, out-of-order paragraphs, misnumbered figures, and (most charmingly) error messages in Korean from their bibliography software. At this stage of things, all that is understandable and excusable.
A few things are presented in a peculiar way, unlike most of the other sc papers I’ve read. Again, that’s more or less ok once you disentangle the coordinate systems on the plots and the like. It can be fixed easily, and probably will be.
To convince anybody to take you seriously enough to test for superconductivity, you have to demonstrate 4 things: (1) 0 resistivity below a reasonably sharply defined temperature, (2) the existence of a critical current above which transition back to normal occurs, (3) the existence of a similary critical magnetic field, and (4) the Meissner effect, or magnetic flux expulsion (totally for Type I and at least partially for Type II).
They did the first 3 of those reasonably believably (even to a guy like me who still has scars from the cold fusion mishegoss back in the day). The Meissner effect, though, gets only partial credit: the diamagentism for the field-cooled & non-field-cooled samples implies an unphysical value of the diagmagentism, and the picture/video of a sample on a magnet only sorta-partially levitates.
The diamagnetism curve has apparently been addressed, as the authors say it was simply a copy-paste error on the graph. The Meissner effect visuals could be explained by the fact that they have a polycrystalline sample (resistance between domain boundaries) of unknown impurities (sometimes coppuer sulfides, other times the Pb/Cu doping may vary across the sample). (Again, this is totally excusable given the rush.) When other people start preparing samples, we’ll see what’s happening here.
It’s not going to revolutionize anything in its current early form:
(1) Frankly, it looks like charcoal. It’s almost certainly not ductile enough to form a wire, and any long thin sample that looks like a wire would be too brittle to wind into a coil.
(2) The critical magnetic field is pretty low, maybe 0.3 Tesla at room temp. For comparison, the tokamak magnets being used by Commonwealth Fusion Systems for their prototype reactors weigh in at 20 Tesla.
(3) The critical current is low. The right thing is to report a current density, but they only report total current without information on sample shape. Still, they topped out at around 250 mA. For comparison, the CFS tokamak magnets run around 40 kA.
IF IT REPLICATES, it’s a fascinating step in phyics (mechanism proposes stressed crystals forming an array of superconducting quantum wells, with currents forming by electron tunneling along the Pb metal backbone… maybe).
But as it is, it’s not an engineering material.
THAT IS ABSOLUTELY OK! This is an early stage compound, all it has to demonstrate that it works. Then tons of material scientists and physicists will start tweaking the recipe, to optimize transition temperature, critical current, and critical field.
Also, I hope, somebody will figure out how use something other than lead. Right now it doesn’t use rare earths, which is good. But it would be better if we could use something with a similar crystal structure to the lead apatite (Lanarkite), but less toxicity.
Then last night all hell broke loose. Kwon made a conference presentation. During that, Lee and the other authors more or less disowned him, said he was fired from the university and the company, and that the first paper was an unauthorized upload by Kwon. Then they retracted the first paper that Kwon apparently wrote on his own and uploaded.
Drama drama drama.
I’m waiting for Argonne, which seems to be on deck for a replication trial next week.
.
Absolutely! It’s not ductile enough for wire, and too frangible to bend around a coil even if you managed to make a long thin piece.
But… the early high-Tc superconductors in the 80s were ceramics, too. Even now, with much more friendly materials, the “wire” in the Commonwealth Fusion Systems tokamak prototype is actually a complex tape with multiple layers mostly for structural support.
Some details here: https://spectrum.ieee.org/fusion-2662267312
Here’s a very nice, more technical presnentation at Princeton by a CFS person, showing the tape strucdture, and how the material had to evolve from microcrystalline stuff to much more complex forms to be useful in an engineering sense: https://suli.pppl.gov/2020/course/20200619_SULI_HTS_Sorbom_Final.pdf
Also note: fusion-relevant REBCO magnets operate at 20T fields and 40kA currents, whereas this new superconductor can’t get above 0.3T fields and 250mA current. Lots of work to do there!
So I hope that gives the right idea: getting from today’s charcoal lump/floaty rock to something with optimized chemistry, easier manufacturability, ductility close enough to wire, and deployable in high fields & high currents took about 30 years the last time it was done.
It’ll be quicker this time, getting from the current charcoal to whatever works, because the incentives are higher. But it almost certainly won’t be simpler.