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

Thanks to CTOnews.com netizens Sancu, Shengyi Youqi and SWRF for their clue delivery! [guide to Xin Zhiyuan] has the Holy Grail of room temperature superconductivity been taken off again? Physicists in South Korea claim to have discovered the world's first room temperature and atmospheric pressure superconductor, LK-99. Can I book the Nobel Prize this time?

Superconducting at room temperature and atmospheric pressure, has it been broken again?

This time, it's a Korean scientist. They claim to have discovered the crystal structure of modified lead apatite, the world's first room temperature and atmospheric pressure superconductor.

South Korean physicists said in the paper that--

All the evidence can prove that LK-99 is the first room temperature and atmospheric pressure superconductor in the world.

The birth of LK-99 means a major breakthrough in the field of room temperature superconductivity and opens a new historical era.

As soon as the news came out, it immediately detonated the Internet and reached the top of the Hacker News in minutes.

If this discovery is true, then we can achieve lossless energy transmission, the global energy consumption problem will be solved from the source, and human beings can gain great power from electric energy.

If we master the controllable fusion at the root, we can even travel long distances in space. And the people who master this technology will undoubtedly lead the world, which is simply science fiction coming into reality.

Paper address: https://arxiv.org/abs/2307.12008

But this time, is it true?

Netizens blew up: can you reproduce it? No matter whether the paper is finished or not, netizens pay homage to it first.

"if it's true, it's nuclear-grade news. "

"this is crazy. I am usually skeptical about these scientific research, but this time, it seems to be credible. Next, we will wait and see whether the experimental results can be reproduced. "

"I can't restrain my excitement. It feels like January 2020, when a huge wave is coming, but no one has realized it yet. It's so good to be alive! Read the paper quickly. "

"Please note that the market is currently skeptical of this paper-even if the probability is as high as 1/6, it will surprise me. "

"if room temperature superconducting electronic devices can really be realized, the prospect of terahertz processor speed will be so attractive! "

"if it can be proved to be true this time, it will be big news. But if you have to wait for the application, it may not be very soon. Numerous examples have proved that the realization of scientific research will lag 20 years. "

"the high-temperature superconductors of the mid-1980s have been mass-produced for nuclear magnetic resonance and fusion start-ups. I don't think all superconductor breakthroughs will take 40 years, for good reason: industry guidance, market discovery and so on have been completed. "

No matter how mysterious it is, let's read the paper carefully.

The world's first room temperature atmospheric pressure superconductor? South Korean scientists say they have chemically synthesized the room temperature and atmospheric pressure superconductor LK99 (modified lead-apatite) for the first time in the world.

Although human beings have known for a long time that the properties of matter come from its structure, so far, we have found that the two main factors that affect the superconductivity of superconductors are temperature and pressure.

They cause small deformation and strain in the structure of the material by causing stress, thus creating an electronic state for superconductivity.

The superconductivity of LK-99 is caused by structural deformation caused by small volume contraction (0.48%), not by external factors such as temperature and pressure.

The superconductivity of LK-99 can be proved by critical temperature (Tc), zero resistivity, critical current (Ic), critical magnetic field (Hc) and Meissner effect.

Figure 1 (a) shows the measured voltage and applied current at different temperatures (298K-398K). Figure 1 (b) is the zero resistivity of the LK-99 film. Figure 1 (c) shows the dependence of the applied current on the applied magnetic field (H). In Fig. 1 (e) and (f), it is shown that the critical current is still not zero at 400K and above 3000Oe (7 mA). The critical temperature of LK-99 is above 400K.

Figure 2: through X-ray diffraction analysis (XRD) and matching with COD database, the author determines that the crystal structure of LK-99 is polycrystal (Apatite: apatite) LK-99 is grayish black, which is the same color as a typical superconductor.

It has a three-dimensional network structure (pictured below) and is a cylindrical column surrounded by an insulated tetrahedral structure.

In the following side view, the spaced cylindrical columns are made up of asymmetric hexahedrons with two opposing triangles.

The researchers found that the volume was reduced by 0.48% due to the replacement of ions in LK-99, because the ion (87 pm) was smaller than the ion (133pm).

The stress occurs in the network part, which leads to the emergence of superconductivity.

However, the heat capacity curve of LK-99 (lower right black curve) does not follow the Debye model, which confirms that LK-99 has a substituted and distorted structure.

At the same time, the EPR signal diagram of LK-99 (below) confirms the existence of quantum well (SQW) on the interface between Pb (1) and phosphate.

On the other hand, SQW is produced between Pb (1) and oxygen phosphate through structural distortion and strain, and its structure is shown in the following figure.

Different from previous studies, the expression of superconductivity of LK-99 is closely related to the formation of SQW.

Josephson et al found that there is a tunneling effect between superconductors, which means that when electrons move between quantum wells (SQW) through tunneling, the resistance will be zero.

Considering that the SQW interval in the LK-99 is expected to be, the tunneling effect between the SQW is likely to occur, and the LK-99 also obtains superconductivity.

In a word, the reason why LK-99 exhibits superconductivity at room temperature and ambient pressure is that the stress caused by ion replacement in LK-99 is not alleviated and is properly transferred to the column-column interface.

This appropriate deformation produces SQW in the interface without relaxation.

At the end of the paper, the researchers said: all the evidence can prove that LK-99 is the world's first room temperature and atmospheric pressure superconductor.

LK-99 has a wide range of applications, including magnets, motors, cables, levitation trains, power cables, quantum bits of quantum computers and THz antennas.

In a word, the birth of LK-99 means a major breakthrough in the field of room temperature superconductivity, which can be said to have opened a new historical era.

In March this year, the physics community caused an uproar when the last one was slapped in the face. Ranga Dias, a physicist from the University of Rochester, claims to have achieved room temperature superconductivity at 21 ℃-LNH, a material made of hydrogen (99%), nitrogen (1%) and pure lutetium, is superconducting at 21 °C and 1GPa.

If what he said is true, there is no doubt that he has made a subversive breakthrough in this field, which is tantamount to taking off the holy grail of physics.

Such a thunder exploded at the physics society in Las Vegas and shocked all the bigwigs on the spot.

However, it is a pity that the Ranga Dias results have not been successfully reproduced by any laboratory since then.

According to the unit cell diagram drawn by Dias, the white atom is hydrogen, the green one is lutetium, and the pink atoms are hydrogen atoms at different sites. The Institute of Physics of the Chinese Academy of Sciences also published a paper "fighting fake", indicating that the binary hydrogen compound (Lu4H23) achieved superconducting transition at 71K (- 202C) and 218GPa, which is neither "room temperature" nor "near atmospheric pressure".

Paper address: https://arxiv.org/abs/2303.05117

In earlier times, the first known superconductor could only remain in a superconducting state of about 25K.

In the late 1980s, researchers discovered the first so-called high-temperature superconductor with a superconductivity of up to 90K-a temperature that can be reached by liquid nitrogen. Scientists think they are on the cusp of a revolution in room temperature superconductors.

The first superconductor, Mercury, was discovered in 1911, but so far, none of the high-temperature superconductors (mainly copper oxide) used in these early experiments showed that their superconductivity remained above about 160K, below the coldest temperature recorded in Antarctica.

There is another predicted path for high-temperature superconductivity. The model shows that hydrogen can be converted into metal under great pressure and superconducting at hundreds of Kelvin.

Several groups of researchers, including Dias and his Harvard postdoctoral adviser Isaac Silvera, claim to have made metallic hydrogen in the laboratory, but hard evidence of the state's existence remains elusive.

Researchers are more fortunate to create metal hydrogen alloys that solidify at lower pressure.

In 2009, researchers claimed to have discovered that the 53rd element was a superconductor. This claim was later withdrawn after it was found that the data behind the results had been manipulated.

In 2015, a team from Germany reported the superconductivity of hydrogen sulphide (H (3) S) at 203K and 155 GPa. Four years later, it was reported that lanthanum hydride (LaH (10)) achieved superconductivity at 250K and 170GPa. The first room temperature superconductor seems to be within reach.

On October 14, 2020, Dias and his colleagues announced on Nature that they had discovered superconductivity in the hydrogen-containing material hydrocarbons (CSH), which contains 287K and 267K and 267K GPa-- the first room temperature superconductor.

However, Dias was later cracked down on counterfeiting and became famous for its "black history".

So, can the results of Korean physicists be successfully repeated this time?

Reference:

Https://arxiv.org/abs/2307.12008

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