German Scientists say not a Super Conductor

German scientists also say that they prepared clean monocrystals of the LK-99 - but the shards pictured are neither homogeneous, neither crystalline for me. They look merely like fragments of ruby glass. Worse then, they're not even black but merely transparent slightly coloured with copper(?) ions. I.e. the level of doping can not be too high there. And the copper appears to be in zero-valent state there - not oxidized one

IMO if LK-99 superconductor works then because long chain of copper (3+) ions embedded within apatite channels attract electrons from outside like hungry hens to a long feeder, which would then create a superconductive phase there. But such a mechanism requires rather high concentration of copper ions in highly oxidized state. The apatite sample presented may have its value in jewellery business, but definitely not in superconductor applications. And similar problem follow all attempts for replication presented so far. This is merely Cargo-cult science - not superconductor one.

Quote from Zephir_AWT

IMO copper sulphide shouldn't be present in material at all: in my theory superconductivity would require presence of highly oxidized lead/copper atoms (which attract and concentrate electrons along their lines) - and sulphide ions would reduce them. So that once you have copper sulphide presented in the sample, it just means that it can not be a superconductor. Cuprate superconductors require long time annealing in oxygen atmosphere during last stage of their preparation. Under such a conditions all traces of sulphide anions would be destroyed.

Not sure of your point. Is your point that the LK-99 is a superconductor according to your theory, or is it not?

Quote from Shane D.

Final nail in the LK99 coffin?

https://www.nature.com/articles/d41586-023-02585-7

Impure samples

In their preprint, the Korean authors note one particular temperature at which LK-99’s showed a tenfold drop in resistivity, from about 0.02 ohm-centimetres to 0.002 ohm-cm. “They were very precise about it. 104.8ºC,” says Prashant Jain, a chemist at the University of Illinois Urbana–Champaign. “I was like, wait a minute, I know this temperature.”

The reaction that synthesizes LK-99 uses an unbalanced recipe: for every 1 part copper-doped lead phosphate crystal — pure LK-99 — it makes, it produces 17 parts copper and 5 parts sulfur. These leftovers lead to numerous impurities — especially copper sulfide, which the Korean team reported in its sample.

Jain, a copper-sulfide expert, remembered 104ºC as the temperature at which Cu₂S undergoes a phase transition. Below that temperature, the resistivity of air-exposed Cu₂S drops dramatically — a signal almost identical to LK-99’s purported superconducting phase transition. “I was almost in disbelief that they missed it.” Jain published a preprint⁷ on the important confounding effect.

On 8 August, the CAS team reported on the effects of Cu₂S impurities in LK-99. “Different contents of Cu₂S can be synthesized using different processes,” says Jianlin Luo, a CAS physicist. The researchers tested two samples — the first heated in a vacuum, which resulted in 5% Cu₂S content, and the second in air, which gave 70% Cu₂S content.

The first sample’s resistivity increased relatively smoothly as it cooled, and appeared similar to samples from other replication attempts. But the second sample’s resistivity plunged near 112 ºC (385K) — closely matching the Korean team’s observations.

“That was the moment where I said, ‘Well, obviously, that’s what made them think this was a superconductor,’” says Fuhrer. “The nail in the coffin was this copper sulfide thing.”

Making conclusive statements about LK-99’s properties is difficult, because the material is finicky and samples contain varying impurities. “Even from our own growth, different batches will be slightly different,” says Li. But Li argues that samples that are close enough to the original are sufficient for checking whether LK-99 is a superconductor in ambient conditions.

Crystal clear

With strong explanations for the resistivity drop and the half-levitation, many in the community were convinced that LK-99 was not a room-temperature superconductor. But mysteries lingered — namely, what were the material’s actual properties?

Initial theoretical attempts using an approach called density functional theory (DFT) to predict LK-99’s structure had hinted at interesting electronic signatures called ‘flat bands’. These are areas where the electrons move slowly and can be strongly correlated. In some cases, this behavior leads to superconductivity. But these calculations were based on unverified assumptions about LK-99’s structure.

To better understand the material, the US–European group⁵ performed precision X-ray imaging of their samples to calculate LK-99’s structure. Crucially, the imaging allowed them to make rigorous calculations that clarified the situation of the flat bands: they were not conducive to superconductivity. Instead, the flat bands in LK-99 came from strongly localized electrons, which cannot ‘hop’ in the way a superconductor requires.

On 14 August, a separate team, at the Max Planck Institute for Solid State Research in Stuttgart, Germany, reported⁶ synthesizing pure, single crystals of LK-99. Unlike previous synthesis attempts that relied on crucibles, the researchers used a technique called floating zone crystal growth that allowed them to avoid introducing sulfur into the reaction, eliminating the Cu₂S impurities.

The result was a transparent purple crystal — pure LK-99, or Pb_8.8Cu_1.2P₆O₂₅. Separated from impurities, LK-99 is not a superconductor, but an insulator with a resistance in the millions of ohms — too high to run a standard conductivity test. It shows minor ferromagnetism and diamagnetism, but not enough for even partial levitation. “We therefore rule out the presence of superconductivity,” the team concluded.

The team suggests that the hints of superconductivity seen in LK-99 were attributable to Cu₂S impurities, which are absent from their crystal. “This story is exactly showing why we need single crystals,” says Pascal Puphal, a specialist in crystal growth and the Max Planck physicist who led the study. “When we have single crystals, we can clearly study the intrinsic properties of a system.”

Lessons learned

Many researchers are reflecting on what they’ve learned from the summer’s superconductivity sensation.

For Leslie Schoop, a solid-state chemist at Princeton University in New Jersey, who co-authored the flat-bands study, the lesson about premature calculations is clear. “Even before LK-99, I have been giving talks about how you need to be careful with DFT, and now I have the best story ever for my next summer school,” she says.

Jain points to the importance of old, often overlooked data — the crucial measurements that he relied on for the resistivity of Cu₂S were published in 1951.

While some commentators have pointed to the LK-99 saga as a model for reproducibility in science, others say that it’s an unusually swift resolution of a high-profile puzzle. “Often these things die this very slow death, where it’s just the rumors and nobody can reproduce it,” says Fuhrer.

When copper oxide superconductors were discovered in 1986, researchers leapt to probe their properties. But nearly four decades later, there is still debate over the material’s superconducting mechanism, says Vishik. Efforts to explain LK-99 came readily. “The detective work that wraps up all of the pieces of the original observation — I think that’s really fantastic,” she says. “And it’s relatively rare.”

Display More

Science prevails! Doesn't mean that a mistake can't lead to new understandings about materials.
Plus, it kind of invigorated the material science space for a bit hopefully.

Quote from Diadon Acs

Science prevails! Doesn't mean that a mistake can't lead to new understandings about materials.
Plus, it kind of invigorated the material science space for a bit hopefully.

Encouraging how the experts in the field handled this. Unlike the CF fiasco, they have been more professional, and now that they concluded the authors were in error, have been rather understanding about it all...so far.

Maybe the difference between then and now is because the superconductor field does not have their sacred $ cow to defend, like the hot fusion scientist's had back in 1989.

Quote

Is your point that the LK-99 is a superconductor according to your theory, or is it not?

Considering that the whole effect observed is weak paramagnetism/semilevitation and temperature of conductivity onset coincides with CuS transition - which is just a bummer - I don't think that synthesis route based on copper phosphide is fertile one.

But I guess there is still more on the bottom. My point is, the "official" synthesis published in 2nd more representative article isn't equivalent to synthesis described roughly in 1st one and which wasn't attempted to replicate yet. IMO there is apparent competition and rivalry between two groups similarly to cold fusion finding in 1986. The first small group is more close to actual know-how of room temperature superconductor which still wants to keep secret. But at the same moment it's forced to publish something for not to lose priority, when 2nd group (containing the boss who is looking after grants and publicity) decides to publish what he (thinks it) already knows.

Quote

Maybe the difference between then and now is because the superconductor field does not have their sacred $ cow to defend, like the hot fusion scientist's had back in 1989.

Yes, the financial pressure is lower than at the case of CF, hence more open and intensive replication effort. But other than that the situation is similar. Which of previous room temperature SC findings 1, 2, 3, 4, 5, 6, 7, 8, 9 was officially attempted to replicate? There is apparent tendency to bury the findings until they don't fit criteria, like the USA origin and inaccessibility of technology for laymen.

Quote from Zephir_AWT

Yes, the financial pressure is lower than at the case of CF, hence more open and intensive replication effort. But other than that the situation is similar. Which of previous room temperature SC findings 1, 2, 3, 4, 5, 6, 7, 8, 9 was officially attempted to replicate? There is apparent tendency to bury the findings until they don't fit criteria, like the USA origin and inaccessibility of technology for laymen.

Maybe so. Hopefully the authors will respond and do a better job backing their claims. At first blush, it appears the sc replicators have a simpler task than those who tried to replicate FP's. Just mix some stuff up, bake it, and voila...a room temp sc.

But then again, those who rushed to the lab in 1989 thought the same thing. It was those who took the time to do it right, that were more likely to be successful back then, and maybe that will turn out to be the case with LK99. Sure do hope so.

At least with LK99, everyone can see with their own eyes if a replication is successful. If it fully levitates, it's a sc, or at least that is how I understand it.

Quote from Shane D.

If it fully levitates, it's a sc, or at least that is how I understand it.

Superconducting frog, I guess:

Never give up never surrender.

One-Dimensional Superconductivity – Key Role of Defects Revealed by Quantum Chemical Calculations of Lead Apatite | NextBigFuture.com

Doped lead apatite has been recently reported to feature superconductivity at room temperature and ambient pressure, which may have huge impact on the

www.nextbigfuture.com

I thought obsidian glass was pretty well understood?

Quote from Seatrout

I thought obsidian glass was pretty well understood?

I live in Obsidian country. It's road-dirt (as long as you grind it up a bit, otherwise it cuts tires - and tyres).
After a rainfall I collect nice specimens by the bucketfull.

It's still used for scalpels!

Black beauty, black diamond, and obsidian are all used in sandblasting. they mix and dump the stuff all over the place

Using it as a mix for a power soak like in a volcano can be interesting.

LK-99 Q-Centre Company Updates RT Superconducting Patent and Claims Half of Thin Film is Superconducting

LK-99 hype faded nearly as fast as it started but I was always under suspicion, there is more under the hood. The LH-99 structure fits well my theory of RT superconductivity and it apparently many scientists already have similar idea too. The only question is, why they're ignored previous RTS announcements 1, 2, 3, 4, 5, 6, 7, 8, 9, which were based on similar structure?

The memo of the LK-99 story is, early replication attempts don't tell much about validity of finding, until they can not replicated by itself. Which is the same story as with premature dismissal of cold fusion finding at MIT and Utah university in 1989. See also:

• Online Comic Explains Why the LK99 Superconductor is So Hard to Make The comic says that no one understands why the structure must be like this , but it's actually easy to understand.

Is LK-99 a Superconductor After All? New Research and Updated Patent Say So

Three Chinese Universities LK99 Samples Could Have One-Dimensional Superconducting Chains

The question is, how they're doing their thin films, because synthesis route of LK-99 published is inconsistent with thin film technology.

It might seem that the recent Chinese scientists discovery of how to make large single molecule thick perovskite 30cm wafers, could be adapted to vacuum deposit LK 99 on to in order to test this in a larger scale. They should also consider doing the deposition in a strong magnetic field to get the molecules to line up correctly. As the latest theories seem to indicate two possible alignments.

Also other studies indicate that oxygen is a preferred doping agent so they might flood the deposition chamber with pure oxygen prior to pumping down to the required vacuum so that only a few stray O2 molecules might remain to contaminate the sample.

In the words of Lloyd Christmas, "So you're saying there's a chance!"

Is LK-99 a Superconductor After All? New Research and Updated Patent Say So (yahoo.com)

Another LK99 Computational Analysis Paper.

Another Computational Analysis Paper Says LK99 Can Be a Superconductor and Modification Will Make It Better | NextBigFuture.com

The s-wave pairing has been proposed for the possible HTS in LK-99. The specific arrangements of atoms with types of orbitals symmetry can, however, lead to

www.nextbigfuture.com

it doesn't matter for LK99, we have diafluid palladium hydride.

Research Continues.

LK-99 Research Continues, Paper Says Superconductivity Could be Possible

Bringing the issues of yield and synthesis to the forefront.

www.tomshardware.com

This isn't LK-99, but LuNH - a different claim of superconductivity that was discussed in the "Playground" thread, earlier this year.

I guessed it might be better in this thread. Please move it, if you feel it shouldn't be here.

https://www.science.org/content/article/another-retraction-looms-embattled-physicist-behind-blockbuster-superconductivity

What about this one.

NASA Validates a New Form of Energy | Utility Dive

I know Henry Lee. But I wouldn't invite him for dinner.