This is another example of why to do great science you need to do great engineering. The original group rushed to publish the paper without polishing the details, and now other groups are struggling to replicate their results.
Semiconducting Transport in LK99 reproduction attempt
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Re: Semiconducting Transport in LK99 reproduction attempt
#142Earlier quoted context omitted.
Not just materials science though. I’m a longtime reader of Derek Lowe’s In the Pipeline blog, and he often emphasizes the trickiness of lab work and lab techniques. But the model we have of science from elementary and high school doesn’t give us room for the random, ephemeral things that come into play in actual experimental work. Our model is methods equal result, every time, even though jiggling your foot a little…
We also don't have a culture of replication. Basically all of the post docs I worked with in the lab lamented how hard it can be to replicate reported syntheses in chemistry wet labs. Everything from humidity and altitude to undocumented "magic tricks" (eg baking something in an oven under vaccuum for a week to get.rid.of.all.the.water.) I heard anecdotes that experiments were sometimes literally only reproducible in…
The simple truth is we don’t have a culture of replication because no one is paying and no one is paying because no one is demanding it as part of the incentive system that the money is part of…
If a prerequisite of publication in a top tier journal was someone having replicated the work… anyone at all… then the quality of write up would improve dramatically because all the stuff that never gets written up would be written up so that the second lab costs them less money to do the replication work, so the second lab doesn’t spent a month failing because they didn’t bake the powder in a vacuum for a week before performing the entire synthesis under dry nitrogen purge when the methodology just said the powder had been dried and the synthesis was performed at ambient pressure in a zero humidity atmosphere…
Re: Semiconducting Transport in LK99 reproduction attempt
#143Earlier quoted context omitted.
So the groups trying to replicate right now are basically wasting their time?
> So the groups trying to replicate right now are basically wasting their time? If a few dozen groups all try and replicate, and there is something to replicate, then odds are good someone will get lucky (birthday paradox and all that). Each individual group is definitely wasting their time, but the aggregate time spent may not be a waste.
The birthday paradox would only apply if we are interested in one group replicating the result of any other group, not the result of the original paper.
It's the difference between "do any people in this group share a birthday" vs "do any people in this group share my birthday".
Re: Semiconducting Transport in LK99 reproduction attempt
#144Earlier quoted context omitted.
For computer science people, I always use the yield on wafers as analogy to explain how hard it can be to nail an experiment right. Usually they understand directly because this is something they can easily relate to.
For those of us unfamiliar with the numbers, what do typical yields look like on silicon wafers?
50–97% with 90% considered “good.”
Re: Semiconducting Transport in LK99 reproduction attempt
#145Everyone in this thread needs to understand that particularly for materials science, and particularly when there is bad methodology documentation, it is really, really normal for early replication attempts to fail. What works in one lab will often need to be adjusted to work in another, with different equipment, altitude, humidity, all sorts of stuff. Making it even worse, apparently the original team can't even get…
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Re: Semiconducting Transport in LK99 reproduction attempt
#146Earlier quoted context omitted.
Not just materials science though. I’m a longtime reader of Derek Lowe’s In the Pipeline blog, and he often emphasizes the trickiness of lab work and lab techniques. But the model we have of science from elementary and high school doesn’t give us room for the random, ephemeral things that come into play in actual experimental work. Our model is methods equal result, every time, even though jiggling your foot a little…
We also don't have a culture of replication. Basically all of the post docs I worked with in the lab lamented how hard it can be to replicate reported syntheses in chemistry wet labs. Everything from humidity and altitude to undocumented "magic tricks" (eg baking something in an oven under vaccuum for a week to get.rid.of.all.the.water.) I heard anecdotes that experiments were sometimes literally only reproducible in…
In that light, industrial processes seem even more impressive.
The super power of modern technology is the ability to perform precise steps on a massive scale and basically forever.
Obviously it takes a lot of effort to keep the machinery running but still, the mere fact that it's running in the first place blows your mind if you think about it.
Modern Machinery multiplies the impact on the world of any human who operates it.
Re: Semiconducting Transport in LK99 reproduction attempt
#147Everyone in this thread needs to understand that particularly for materials science, and particularly when there is bad methodology documentation, it is really, really normal for early replication attempts to fail. What works in one lab will often need to be adjusted to work in another, with different equipment, altitude, humidity, all sorts of stuff. Making it even worse, apparently the original team can't even get…
This comment intrigued me, so I pulled together some information. The first paper submitted is titled "The First Room-Temperature Ambient-Pressure Superconductor." It lists three authors: Sukbae Lee, Ji-Hoon Kim, and Young-Wan Kwon. Its timestamp is Saturday, July 22, 2023 at 07:51:19 UTC. [1] The second paper submitted is titled "Superconductor Pb10−xCux(PO4)6O showing levitation at room temperature and atmospheric…
The second paper's "semiconductor" claim is no less than the first.
Re: Semiconducting Transport in LK99 reproduction attempt
#148> 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. So what about the video[1] that shows magnetic levitation occurring? Since the linked article was unable to reproduce this effect, it seems there are two possibilities: 1. The video is fake (which is really, really hard…
Apparently a new paper is supposed to come out from the original authors about the production method [0]. So it really is unclear whether everybody generates the same material. It's a shame that these papers were published before they were polished by the authors. [0] https://forums.spacebattles.com/threads/claims-of-room-tempe...
> It's a shame that these papers were published before they were polished by the authors.
We've seen no evidence that they were.
Re: Semiconducting Transport in LK99 reproduction attempt
#149Everyone in this thread needs to understand that particularly for materials science, and particularly when there is bad methodology documentation, it is really, really normal for early replication attempts to fail. What works in one lab will often need to be adjusted to work in another, with different equipment, altitude, humidity, all sorts of stuff. Making it even worse, apparently the original team can't even get…
It's not dissimilar to the way food recipe books work.
Creating a dish, replicating the dish, writing a recipe, getting competent cooks to follow the recipe, getting non-competant cooks to follow it, and so on. [1]
It all leads to multiple revisions and takes a lot of time.
And this is for -food-. Imagine doing it for something a lot less tolerant of variation.
[1] old recipes start with "pluck 2 chickens" because, you know, someone followed the recipe and didn't pluck the chickens...
Re: Semiconducting Transport in LK99 reproduction attempt
#150What they have produced is clearly not LK-99.
They write that: " As shown in Figure 9, the x-ray diffraction spectrum of the ground powder of the finally sintered product is highly consistent with the x-ray diffraction spectrum reported by Lee et al.[3] and coincides well with the diffraction pattern of the apatite. This proves that we have successfully synthesized the modified lead-apatite as Lee et al.[3.4] "
(First off, you need to pay to the spectrum swear jar. an XRD pattern is a pattern, not a spectrum, it resolves space, not energy.)
But looking at figure 9 shows that the material is not the same. They are missing a peak at ~17.5 degrees, and have an extra one around 25 degrees.
Further, all the peaks seem to be shifted about the same amount from the LK-99 structure, as the LK-99 is from pure lead-apatite. This indicates that they have an even smaller unit cell. So if the .5% compression in the original LK-99 paper is correct, there could easily be an overcompression present in this article.
All the XRD pattern tells you is that they produced something wrong, an that it did not superconduct.
It makes it impressive how pure the phase was in the original LK-99 paper.
I will however say that there are some problems with the XRD pattern in the original paper too: They did not write which energy the XRD was measured at, one would then guess that it is Cu-Ka, but who knows. Under any circumstances, a peak should not be missing completely from a powder measurement (if it was a pellet, it could be missing due to orientation effects)