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Semiconducting Transport in LK99 reproduction attempt
71–80 of 269 posts
Re: Semiconducting Transport in LK99 reproduction attempt
#72> In addition, when a pressed Pb10-xCux(PO4)6O pellet is located on top of a commercial Nd2Fe14B magnet at room temperature, no repulsion could be felt and no magnetic levitation was observed either. Unless we assume the original paper's authors were straight up lying, it sounds like this paper's author didn't end up with exactly the same material?
They mention the possibility of a mistake when measuring resistivity, which has already been discussed. But yeah, the partial levitation is not a mistake. Their abstract suggests LK-99 is a "highly insulating diamagnet", but they are not even able to "detect any reliable diamagnetic signal" with their instruments. I'd rank the possibilities as: fraud, a different material, or some comical series of bizarre mistakes a…
I think it’s disrespectful to accuse scientists of fraud in public, when there’s zero evidence of any fraud. It’s just not a good look.
Re: Semiconducting Transport in LK99 reproduction attempt
#73Research out of Berkeley, 1 Aug 2023: theoretical analysis suggests high-Tc superconductors from apatite possible, points to synthesis challenges. > 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, cha…
Wow, August 1 2023 hasn't even come yet. Superconductivity is amazing.
Arxiv releases preprints at midnight UTC, so if you’re in the US you might catch a paper dated Aug 1 on the evening of July 31
Re: Semiconducting Transport in LK99 reproduction attempt
#74We are so so back. Cannot wait to see the new era. Feeling real bad for the doomers
Re: Semiconducting Transport in LK99 reproduction attempt
#75For the non-chemists/physicists:
Recently[1], there was an exciting claim that a new type of material could conduct electricity perfectly at room temperature (this is what is meant by "superconductivity")[4]. This material was a version of lead-apatite [2], a type of mineral, that was altered with certain additions and made by combining two other materials, lanarkite and copper phosphide.
The researchers writing this report wanted to check if this claim was true. So, they made the same types of materials (lanarkite, copper phosphide, and the altered lead-apatite) and tested how they conducted electricity and reacted to magnets.
What they found was that lanarkite (Pb2SO5) didn't conduct electricity well at all, and copper phosphide Cu3P) conducted electricity similar to a semiconductor [3]. The altered lead-apatite, which was supposed to be the superconductor, behaved more like a semiconductor (a type of material that can sometimes conduct electricity, depending on conditions).
Also, a key property of superconductors is that they repel magnets. But when the researchers put a magnet near their lead-apatite, there was no repulsion.
Because of these tests, they're suggesting that the original claim about this room-temperature superconductor should be re-examined more carefully. It doesn't seem to behave like a superconductor in their tests.
[1] https://news.ycombinator.com/item?id=36864624
[2] https://en.wikipedia.org/wiki/Apatite
Re: Semiconducting Transport in LK99 reproduction attempt
#76Research out of Berkeley, 1 Aug 2023: theoretical analysis suggests high-Tc superconductors from apatite possible, points to synthesis challenges. > 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, cha…
Do many materials yield similar conclusions? If so, then this is just confirmation bias, but if the analysis is rare, then it might be something?
Re: Semiconducting Transport in LK99 reproduction attempt
#77Earlier quoted context omitted.
I think a huge part of that is translation: imagine what you might sound like if you wrote a press release for or tried to explain to a layman some project you're involved in, and then had it translated to Korean. Some benign description of why room temp atmospheric pressure superconductors are interesting becomes 'a brand-new historical event that opens a new era for humankind'.
> imagine what you might sound like if you wrote a press release for or tried to explain to a layman some project you're involved in, and then had it translated to Korean. My understanding is that this was supposed to be a (draft of a) research paper, not a "press release". The article certainly doesn't read like laymen are the intended audience. > Some benign description of why room temp atmospheric pressure superco…
Wasn’t the paper leaked by the industry guy? Didn’t he edit it to include himself?
He might have jazzed up some other wording as well.
It’s worth giving the benefit of the doubt to the final product. Let’s get some replication (or not) and go from there.
Re: Semiconducting Transport in LK99 reproduction attempt
#78We are so so back. Cannot wait to see the new era. Feeling real bad for the doomers
Huh? The linked paper abstract says failed to reproduce the result. And they're not the only ones:
https://forums.spacebattles.com/threads/claims-of-room-tempe...
We'll see where we are in a couple weeks, but it's not looking good.
Re: Semiconducting Transport in LK99 reproduction attempt
#79Doesn'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 ceram…
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-temperatur...
Re: Semiconducting Transport in LK99 reproduction attempt
#80Earlier quoted context omitted.
Sounds like they have it the wrong way round. Considering the uncertainty surrounding all of this, and the initial problems with replication, why would Nature publish this before it has been independently replicated? Not sure what they're worried about here. They already have priority, and if this replicates, every journal on Earth will be fighting over the privilege to publish it.
Most likely the peer review process will include replication.
Normally (at least in my field), that’s beyond the scope of peer review in the traditional sense. Peer review typically just involves review of just the material submitted to the journal (manuscript, data, maybe code depending on its size and complexity). Depending on the experiment, reproducing a result may require resources, equipment, or skills unavailable to the reviewer or that cannot be acquired in a reasonable amount of time needed for the review.
Peer review serves basically as a smell test where capable experts certify that the paper is novel, interesting, properly justifies its claims, and contains enough detail to reproduce the results. It is not uncommon for only a few labs to contain all of the expensive, specialized equipment to reproduce an experiment, and getting that experiment working (if it is reproducible) can take a significant time commitment from multiple individuals in a lab. Also keep in mind that reviewers are normally not paid for their services, journals typically want at least two independent reviewers (who they pick, sometimes with input from the author to narrow down who has the background to perform the review), and going from submission to publication is typically a many-month process without the high standard of reproduction.
Reproduction happens in the manner that is going on right now. If your publication makes waves, people will want to build on your result and either reproduce it as a first step or conduct a related experiment that adds evidence to support the hypothesis. This way is far more practical, but the devious thing is that, if you lie and manipulate your data, some poor grad student might waste two years of their PhD trying to get your thing to work.
Having journals or some independent body fund reproduction themselves runs into both capital challenges and the problem of attracting a large enough number of capable scientists to cover every discipline who would only want to work on reproduction full time. As nice as that would be, I’m not sure such a venture would work in the real world.