Source | Qubit
Author | Sunborn
The LK-99 sent to the late director was pushed down by Nature again this morning. In the headline article on the front page, the headline clearly reads " LK-99 is not a superconductor ".
What a fat thing, is this directly nailing the coffin board?
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Not too much~ Although the title is fierce, but to be more precise, Nature is a summary of the entire "Send Pai" point of view:
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On August 14, LK-99 single crystal was synthesized by the Max Planck Institute in Germany. The crystal is transparent and insulating, and the existence of superconductivity is excluded;
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On August 9, Spanish DIPC and Princeton and other research institutions jointly performed X-ray imaging on LK-99, and analyzed that this material is more likely to be a magnet than a room temperature superconductor;
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On August 8, the Chinese Academy of Sciences analyzed that the so-called "superconducting" phenomenon of LK-99 is likely to be the decrease in resistivity caused by the phase transition of the primary structure of Cu₂S at around 385K;
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On August 7, a Peking University team paper believed that the semi-levitation phenomenon of LK-99 was caused by ferromagnetism.
Nature also quoted Monash University physicist Michael Fuhrer as saying:
The nail in the coffin is Cu₂S. (Original words) It is now the responsibility of the Korean team to share the original samples and convince others.
Well, no matter how you say it, the smell of gunpowder smoke is a bit strong. It's no wonder that netizens can taste the taste of this melon after eating it: I'm afraid Nature is forcing the palace, isn't it?
LK-99 "Jipai" one hammer after another
Nature's tone of voice is inseparable from the continuous heavy hammering of LK-99 "Send Pai". Taking the latest developments in these two days as an example, abroad, the Max Planck Institute of Solid State Physics and Materials invested heavily and directly synthesized Pb₁₀₋ₓCuₓ(PO₄)₆O single crystal, excluding the influence of Cu₂S. In China, the Chinese Academy of Sciences has also published a new paper on arXiv, studying LK-99 samples from three independent groups at the microscopic scale, and measuring the magnetic properties of each phase on the sample surface. The results of these two papers together point to a conclusion:
The abnormal electrical behavior observed in the LK-99 material may originate from impurity phases such as Cu₂S.
Max Planck: Single crystals are transparent and insulating, ruling out superconductivity
Specifically, the Max Planck Institute used the floating zone method to synthesize the samples. This approach avoids the introduction of sulfur into the reaction and eliminates the effect of Cu₂S. The synthesized Pb₉Cu(PO₄)₆O single crystal looks like this:
The crystals are purple-transparent and, more importantly, resistive in the millions of ohms—an insulator . In magnetic measurements, the researchers found that the single-crystal samples exhibited slight ferromagnetism and diamagnetism. In the temperature range of 2-800K (-271°C-526°C), the researchers observed no anomalies that would indicate a phase transition. Therefore, the researchers believe that the possibility of room temperature superconductivity of Pb₉Cu(PO₄)₆O crystals can be ruled out. This paper also mentioned that Cu₂S impurity phase often appears in polycrystalline Pb₁₀₋ₓCuₓ(PO₄)₆O samples, and the phase transition of Cu₂S may lead to abnormal electrical behavior of polycrystalline samples (there is a structural phase transition around 398K accompanied by insulation - metal transformation). Cu₂S itself is not a superconductor.
Chinese Academy of Sciences: Measuring the magnetic properties of each phase of the sample surface on a microscopic scale
The latest research of the Chinese Academy of Sciences collected LK-99 samples synthesized by three independent groups. Unlike the Max-Planck Institute, the researchers did not focus on single crystal synthesis, but chose to perform chemical, magnetic and electrical measurements of different phases on the sample surface directly at the microscopic scale. The technical means used include optical microscope, scanning electron microscope, AFM/NV and so on.
They found that the Cu₂S phase region of the sample exhibited diamagnetism, while the Pb phase region exhibited mixed diamagnetism and weak ferromagnetism. Again, the paper concluded that no superconducting transition was observed, ruling out the possibility of room-temperature superconductivity. The paper also further studies the current path jump and resistance state change caused by the Cu₂S phase transition, and believes that a large part of the diamagnetic response of LK-99 can be attributed to these copper-rich impurities.
In fact, the "guidance" did not rest
Having said that, the "Jipai" warhammer was soaring, and even Nature revealed that "Jiji is very likely", but the "Guipai" was not completely passively beaten. Just in the early hours of this morning, Zhihu user AD9hxd uploaded a new video, claiming that his LK-99 sample had "suspected pinning phenomenon".
Previously, this netizen posted a live broadcast to reproduce LK-99 and announced the complete "alchemy" plan. (See the link at the end of the article for details) Things have progressed to this point, perhaps the same sentence, "The Korean team has the responsibility to convince others." Whether LK-99 is sent or guided, we still have to be patient and eat melons scientifically.
