Shulou(Shulou.com)11/24 Report--

Thanks to CTOnews.com netizens Yunfu Qianqiu, Ishihara Rimi Happiness, 1520111 soft media users, suitcases, sweet peanuts, kinja, Sancu clue delivery! South Korea denies itself?

Just now, the Yonhap news agency said that after scientific research, the Korea Superconducting Cryogenic Society (KSSC) thought:

LK-99, the current evidence is not enough to prove its superconductivity.

The organization, which was just announced yesterday, had intended to take samples from the team to cross-test two properties, zero resistance and complete diamagnetism.

But here comes the thing about drama.

The Korean research team rejected the request for a sample, for the following reasons:

The paper is under review and samples can not be submitted until 2-4 weeks after the end of the review.

As a result, KSSC only gives the following reasons based on papers, videos and data:

It does not fully show the Meissner effect (complete diamagnetism).

The data in this paper are also different from the general superconductors.

The committee also believes that there are many materials that are diamagnetic even if they are not superconductors.

The news has been hotly discussed by netizens on Zhihu, and they have begun to question it-they didn't even get the sample!

So the point that needs to be refuted is that this report by Yonhap news agency does not definitely deny the superconductivity of LK-99.

Therefore, for the recent news related to room temperature superconductivity, we still need to eat melons calmly.

After all, scientists all over the world are working overtime to do the reproduction work.

Just in the early hours of this morning, Professor Sun Yue of the superconducting research team of the School of Physics of Southeast University released the latest results in bilibili.

LK99, zero resistance has been successfully observed at atmospheric pressure below 110K (- 163℃).

In the words of Professor Sun:

It may be evidence of superconductivity, but whether it is superconducting or not remains to be confirmed by further experiments.

It is worth emphasizing that this study does not mean the confirmation or discovery of room temperature superconductivity.

However, this does not affect its value and significance, as Professor Xi Zhixi of South China University of Technology commented in Zhihu:

Very shocking, even more shocking than the result of Huake two days ago; far more than expected!

As a result, this study has also attracted a lot of onlookers, with more than 2.51 million views as of press time.

Next, let's take a closer look.

(note: the content of this article has been authorized by Professor Sun Yue. )

In the released video, Professor Sun Yue opened the paper and explained it in the way of "looking at the picture and talking".

The first is a chart of the results of X-ray diffraction (XRD) experiments:

Among them, (a) and (b) on the left represent the XRD results of the two precursors, and (c) on the right represent the XRD results of four samples.

Comparing them with the results previously released by the South Korean team, we can see that XRD is very consistent, and Professor Sun said:

We are a little purer than their samples, and we can see that the Cu2S peak is already very small.

Then there is the highlight of the experiment-the result of zero resistance.

The team began to measure from 300K to low temperature, and the current was 1 Ma. The results are as follows:

Professor Sun said that the sample used in the test itself is brittle, and it is difficult to make it into a regular shape (but also to save time), so when the sample is in an irregular shape, the resistivity is measured by the four-lead method.

From the experimental results, the semiconductor behavior of the material appears at high temperature, and the key is that the resistance of the sample is basically reduced to 0 at 110K.

As for the strange decrease in resistivity at 250K, Professor Sun's explanation is:

It could be made of electrodes, maybe it's not very clean.

Similarly, in this experiment, the team added a magnetic field to measure the superconducting transition of the sample.

From the results, the superconducting transition of the sample is still relatively stable, and the TC Zero has only a little change.

Professor Sun said:

We actually saw a steep drop in resistance similar to the superconducting transition in the afternoon of August 1, but at that time our resistance did not reach zero.

So we then stepped up the selection of samples and tested a total of six samples, but zero resistance was observed on only one sample; the rest was semiconductor behavior.

In addition, for this zero resistance sample, we have also measured the Meissner effect, and no complete diamagnetism has been observed.

Therefore, we speculate that the zero resistance in the sample is caused by superconductivity, so the superconducting component is still relatively low.

Room temperature superconductivity has not been confirmed, but it is also an improvement. As we just mentioned, Professor Sun's team's experiment is not at room temperature, but below 110K.

But its greatest significance is to "prove that LK99 does have something, which is worthy of further study by scientists." As bilibili Up said in "Turing's Cat":

However, some netizens have questioned the accuracy of the experimental results. Professor Xi Zhixi of South China University of Technology believes that:

This does not need to be entangled, PPMS is the world's general physical property measurement system, measured its detection limit has no resistance, that is, zero resistance, which is recognized.

Generally speaking, if the resistance falls from room temperature to three or four orders of magnitude, superconductivity may already exist, and the result of Dongda is even better.

In addition, Professor Xi Zhixi also explained the problem that the transition temperature zone was too wide:

This is the normal state of high temperature superconductivity. Even the bulk ybco has a transition range of more than 10 K and the width of the mixed phase is very wide.

The so-called mixed phase, sometimes called prematched phase, is that the Cooper pair has already appeared, but because of the pinning of the vortex, it is not yet fully condensed. It's completely condensed, which is the Meissner phase.

And Professor Xi affirmed the experiment:

In any case, this has been a very exciting result. The range of imagination can be slightly increased so as to lose.

Finally, Professor Sun's team's paper has been submitted to arXiv, interested partners can squat for a while.

One More Thing

Last night, Qufu normal University tested the resistance against magnetic LK-99 for the first time.

The test results show that the sample still has a large resistance in the range from room temperature to 50K (- 223.16 ℃), and there is no sharp drop in resistance or zero resistance in the testing process.

In this regard, according to the Interface News report, Liu Xiaobing, a professor at the School of Physics and Engineering of Qufu normal University, said:

Netizens mentioned that LK-99 is the best material for human maglev technology, which needs to be treated rationally and objectively. Any new material has a long way to go from discovery to final large-scale application. What's more, the current understanding of LK-99 is still very limited.

For the "global top current" of room temperature superconductivity, we still need to do and observe.

Reference link:

[1] https://www.bilibili.com/video/BV1pM4y1p7u5/?spm_id_from=333.337.search-card.all.click&vd_source=7db76f4680fb17cddf55f19665bb2efd

[2] https://www.zhihu.com/question/615350352/answer/3147560576

[3] https://www.reddit.com/r/singularity/comments/15g63n1/the_korean_society_of_superconductivity/

[4] https://mp.weixin.qq.com/s/0pfcfy4h9NJ2MkOL7_LjRQ

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