I'm not following you. The compound is specified, the process is what is poorly specified and the researchers more or less admit that they do not exactly know what the right method is. This makes it a lot harder to replicate and may well cause a lot of attempts to misfire before someone finds something that works or we give up on the search. What TFA here suggests is that there are some potential complications in manufacturing this that would explain why the original researchers had problems trying to make the compound, the number that I recall is that '1 in 10' tries resulted in a working sample.

That would also be a fantastic way to pull a hoax, because it will result in 10x more effort spent on your hoax. If it turns out that it was a hoax I think the original researchers will find immense gratitude from Pons and Fleischmann for taking over the top spot for the textbook example of bad science. But for now, as far as I can see the jury is still out, and if anything the paper linked here actually improves the chances of it being real a bit more than it is offset in the other direction by a failed replication attempt.

Then why do we have separate names for Graphite and Diamond? Same element, different molecular (crystalline) structures. If CuO25P6Pb9 can exhibit superconducting properties, and reproduction attempts are failing, then there must be a specific isomer that needs to be achieved, the creation of which is not described in the LK-99 paper. I'm just trying to understand how to wade through this stuff, I could be wrong, and I dropped solid state physics because I hated it, but that's how I currently understand the situation.

Edit: s/isomer/polymorph

Same molecular structure entirely different crystal lattice.

It is the formation that is different not the molecules. C = C. They are technically allotropes:

https://en.wikipedia.org/wiki/Allotropy

And just like here that's a function of how the bulk carbon got to be formed, under extreme pressure and temperatures or less pressure and temperature. It's the recipe that makes the difference, not the ingredients.

As far as I understand, we're saying the same thing.

    isomer
    /'aɪsəmər/
    noun
    a compound that exists in forms having different arrangements of atoms but the same molecular weight

I'm using isomer to refer to possible different arrangements of "the LK99 compound". I see you're saying allotropes refers to diamond vs carbon (allotrope referring a single element vs isomer referring to compound).

That raises a question, what's the name for different crystalline structures of the same compound? Is that still an isomer or something different? I'm out of my element here.

An isomer can have different valences but still have the same overall chemical formula.

So just for an example (I have no idea how to put a tetrahedron in a comment :) ) a chain of C-C-C-C and C-C=C-C (which you likely can not synthesize) would be an isomer but C-C-C-C in one crystal lattice versus C-C-C-C in another crystal lattice would be allotropes.

The carbon in graphite sits in sheets (hence the possibility to form graphene), whereas the carbon in a diamond always forms three dimensional lattices.

edit nah: bad example, sorry, I can't find a good way to visualize this in text the 2nd C-C-C-C chain should have the last C dangling from the 2nd down.

edit2: examples are wrong, I should have used a more complex molecule for the isomer and the carbon can have either three or four other carbons hanging of it for the allotrope. tricky...

Just double checking, the definitions I'm finding for allotrope are specific to a single element.

    allotrope
    /'ælə,troʊp/
    noun
    a structurally different form of an element

I'm having trouble finding allotrope used to refer to different forms of a compound.

https://www.differencebetween.com/difference-between-allotro...

Yes, you're right, I should have used a more complex example for an isomer.

Isomers are structurally different. Allotropes refer to variations of the same element.

You're looking at the word "polymorph": "(chemistry, geology) Any substance or mineral that forms different types of crystal."

Thank you.

Pons and Fleischmann, not Jan Hendrik Schön?

Wow that's a bad one, I never even knew about it, thank you for pointing that out. And yes, he's probably worse, with Pons & Fleischmann I never managed to rule out that they themselves were 'true believers' that had deluded themselves rather than fraudsters. But with this guy there is little doubt.

Oh yeah, he is absolutely fucking wild. There's a great documentary on him, here's part one, the other two parts of the documentary are also on YouTube on the same channel: https://youtu.be/nfDoml-Db64

> Pons and Fleischmann ... bad science

They found a new phenomenon, that took years to explain. They didn't do anything bad.

Defining LK-99 as “the thing you get from following the steps in this paper” and not “the allegedly superconducting material these guys have a sample of” is silly.

You say potato... The paper is fucking vague on all counts, from synthesis to result. "LK-99" at this point is understood to be most likely a mixture of compounds. It is not fully defined, it is not one "thing," it's broad proposal that encompasses a family of materials.

Essentially all of my knowledge of materials science comes from reading HN's discussion of this over the last ten days, but I've read repeatedly that these kinds of synthesis processes are not very reliable. Even with well known materials with well known "recipes," someone trained can follow a procedure apparently to the letter and get no result, and then repeat the procedure apparently the same and get a good result.

Semiconductor yield at high end fabs can be lower than 20%. If you tried that process at a new fab and wound up with a complete failure, would you say "well that process just doesn't produce any semiconductors" or would you think you might need to refine the implementation of the process.