New China LK99-Like Superconductor Research and Imminent Patent

(1) Understanding of the original formula

As we all know, the synthesis method of LK-99 is very simple (quoted by a financial blogger). Pyrite Pb2SO5 + cuprous phosphide Cu3P can be synthesized simply. However, this reaction mechanism has always been questionable.

One school of thought is that cuprous ions are conducive to crystal doping, so Cu3P is deliberately used, and the process of P replacing S is used to achieve Cu doping. Mechanistically, DFT seems to be able to explain this problem. But many people miss the core of this response. That is, Cu and P are already bound at the beginning. So can we change our thinking and understand that lead with S is doped into copper phosphate?

Pb2SO5+Cu3P→Cu3PO5+Pb2S→At this time, sulfur begins to replace O in the phosphate group, and at the same time fills in the vacancies, and Pb fills the copper salt→PCPSOSO. This seems to be a mechanism. The essence of Cu3P is actually to provide a strong reducibility, allowing S to better replace O.

(2) Metaphysical process

Divert to another topic.

In LK’s thin film patent, it can be noted that the chemical equation given is actually Pb10-xCux(PO4)S. This has been given in Zhihu transfer very early, which means that the S element must be very important. . This actually hinted at the importance of sulfur when I submitted the first preprint. I deeply suspect that the chemical formula given in the first preprint of LK-99 is actually a smoke bomb. Then he tricked a group of people into rushing forward but returned without success.

In fact, our initial thought was that 1 copper seemed to be a bit too little. At least 3 to 4 coppers were reliable, so we used hydroxyapatite as a precursor and started sintering to prepare apatite, but in fact Yes, when x>2, Cu can no longer be doped. LK-The 0.9~1.1 given in the original article is actually very reasonable. When the element in the hole is oxygen, it is difficult for Cu to enter. So, at this time, Teacher Chen took action and began to calculate the replacement of elements in the holes. He started to try replacing O with S. Of course, as mentioned before, the effect looks good.

But this time we seem to have discovered another problem, which is difficult to solve when repeating. That is, if co-precipitation is used, the magnetic properties will be rubbish! It is a simple diamagnetic property. Then I carefully checked the experimental records. The premise of the synthesis is that it is best to start directly with nano-copper phosphate. In other words, you cannot prepare a Cu+Pb mixed solution and then add phosphate to precipitate it. Instead, you need to prepare copper phosphate precipitate first, then add Pb to the solution, and then add phosphate. This is a metaphysical process. The key to this process may be the coating of nano-salt, but I don’t know much about the specific reason.

The picture below is a structure for Pb4Cu6(PO4)(O/S).

(3) High voltage to achieve S doping

I have always thought that SukBea Lee’s method is invincible, but I have never understood the secret. Why use such a complicated equation to implement the entire process. Later, when I thought about it carefully, I realized that it was actually pressure! Although it was explained during the experiment that the vacuum tube must be pumped to a very low vacuum. But everyone has overlooked that the product of this reaction contains S2↑. The extra gas will cause the vacuum tube to actually be under high pressure, which means that the value of P(S2) is very high! When P(S2) is very high, it is possible to replace O in holes and acid radicals. In the end, it is the formula PCPSOSO given by Professor Jin. It is precisely because the internal pressure may be different that when everyone reproduces, the results are varied.

So either use low temperature to prevent the sulfur from escaping and doping it, or use high pressure to slowly replace it. This synthesis is really interesting~

(4) Strange conductivity

I recently tried the synthesis of PCPSOSO powder (a lot of metaphysical variables are involved). When it came to the raw materials, Mr. Light Machine and Mr. Guan made it for me. I’m so happy! Use a briquetting machine to press the powder together and sinter it at 100°C. Because there is no professional electrical measuring equipment, everyone went home during the Spring Festival, so we can only test it with a broken multimeter. Probably, the room temperature resistance is a little lower than that of copper (copper is about 3Ω, PCPSOSO is about 2Ω, if my multimeter is short-circuited, it will be 1.9~2.0Ω, magic). It can only go so far. If my brothers in Beijing can help me measure the resistance using the four-wire method during the holidays, please contact me as soon as possible. Urgent to death~~~~~~~~~~. Teacher Qiao and Brother Xi both celebrated the New Year, and no one tested me.