Chapter 340: Searching for the mechanism of high-temperature superconductivity
In the conference room, Xu Chuan took the notebook from Fan Pengyue and flipped through the data inside.
The researcher who discovered the ultra-low-temperature superconducting copper-carbon-silver composite material is called Song Wenbo. He is a professor recruited from Wuli University. His previous main research field was materials chemistry.
This time Professor Song was able to explore ultra-low temperature superconducting materials, half relying on experience and half relying on luck.
He did not follow the powder metallurgy method of traditional materials science, nor did he follow the high-temperature and high-pressure synthesis method commonly used to study superconducting materials to study copper-carbon-silver composite superconducting materials. Instead, he adopted the development route of nanomaterial preparation and molecular modification.
He first prepared copper-carbon-silver composite materials through nanometer means, and then used vapor deposition to control and adjust the subtle atomic structure.
Compared with the conventional powder metallurgy method for preparing copper-carbon-silver composite materials, this new method solves the problem of weak interface bonding between copper and carbon and the presence of a large number of holes in the composite material.
Compared with high-temperature and high-pressure superconductor research methods, it also avoids the shortcomings of copper atoms and carbon atoms not reacting even at high temperatures and extremely poor wettability.
I have to say that Wuli University, which ranks among the top five domestic universities in the field of materials research, is quite capable.
An above-average, not top-notch professor of materials chemistry, with sufficient experience and coping methods in conceiving and developing new materials.
If we want to talk about the shortcomings, it is that in the process of two-dimensional film deposition, a binder is used, even if it is only a trace amount of binder, this destroys the purity of the copper-carbon-silver composite material itself to a certain extent.
This not only means that it requires a lower temperature to make this thin film material reach the superconducting energy gap. It also means that the performance of the material itself is greatly reduced.
"It's interesting. I'll call Professor Song and ask him if he has time now. If so, please ask him to come over. I have some questions and I want to consult him."
After flipping through the information on the computer, Xu Chuan raised his head with interest, tapped his fingers lightly on the table, and said to Fan Pengyue.
To be honest, the value of this ultra-low-temperature superconducting copper-carbon-silver composite material itself is actually not that great.
First of all, the material developed by Professor Song is a two-dimensional thin film structure, and it is still very difficult to process it into wires or other shapes of superconducting materials.
The second step is to achieve superconductivity at a temperature of 43.k (about -30 degrees Celsius), which has already been achieved outside.
For example, Cern's Large Strong Particle Collider.
Accelerating particles requires an ultra-strong magnetic field, and strong magnetic fields require superconducting materials to reach their limits.
The LHC particle collider uses niobium-tin alloy. After being cooled by liquid helium, this material has become superconducting in a normal pressure environment and can be mass-produced.
Aside from low-temperature superconductivity, high-temperature superconductivity has actually been studied for a long time.
As early as 1987, scientists from China, the United States, small island countries and other countries all discovered that 'barium-yttrium-copper oxide' has tc in the liquid nitrogen temperature zone, and thus has superconductivity.
(tc refers to the critical temperature, which is the temperature at which the material changes from a normal state to a superconducting state. For example, mercury, when the temperature is slightly lower than 4.k, the resistance of mercury suddenly disappears and it exhibits a superconducting state, so the tc of mercury
It is 4.k, about minus 68.9 degrees Celsius.)
However, due to the fact that copper oxide superconductors are very brittle ceramic materials, you cannot draw them into thin wires. In addition, the manufacturing cost is very high, and they will fail if they are contaminated by impurities. High-temperature superconductors have not been able to be used in industry.
.
Therefore, the temperature superconductivity of 43.K alone does not have much practical value.
Not only does it require liquid helium freezing to be superconducting, it cannot be industrially produced.
However, he found something very interesting in this information.
If we can figure it out, maybe we can explain the superconducting principles of high-temperature superconducting materials from another angle.
To know the basic principles of high-temperature superconductivity of superconducting materials, let alone the early 2000s, even in more than ten years, no real explanation has been found in later generations.
Even if he developed room-temperature superconducting materials in later generations, he could not explain the reason for the existence of room-temperature and high-temperature superconductors.
If it were in other fields, this would be almost impossible or extremely difficult.
If the theory is not yet formed, how can practical results be achieved?
But in the field of materials science, it is ordinary to have no theory but to accidentally come up with experimental results.
Many materials used in society today actually have results first, and then study the results to obtain the theory.
If the superconducting principles of high-temperature superconducting materials can be explained clearly, this will definitely be a huge improvement for the development of superconducting materials.
Fan Pengyue nodded, took out his mobile phone from his pocket and made a call. After asking for a while, he hung up the phone.
Not long after, there was a knock on the door outside the conference room.
Xu Chuan said: "Please come in."
Immediately, the door opened and a middle-aged man wearing gold-rimmed glasses walked in.
"Mr. Fan, are you looking for me?"
Song Wenbai walked in and asked, but his eyes fell on Xu Chuan who was sitting at the desk.
The familiar figure made him involuntarily stunned for a moment, and he asked doubtfully: "Are you Academician Xu?"
When the Chuanhai Institute of Materials poached him, he knew that the real owner behind the laboratory was the famous Professor Xu Chuanxu.
He recognized Xu Chuan, but he was a little doubtful whether it was true.
Because from joining the company until now, let alone him, most people at Sichuan and Hai Materials Research Institute have never met this real boss.
So even though I saw the real person now, I still doubted whether I saw it wrong.
Opposite me, Fan Pengyue looked at Xu Chuan and said with a smile: "You said, you have been working as a shopkeeper for a long time, and even the employees in the company don't know you anymore."
Xu Chuan ignored Fan Pengyue. He smiled at Song Bai and said, "It's me. Professor Song, please sit down. I'm here to see you this time. I mainly want to consult on some questions."
Song Wenbai walked over quickly and asked nervously: "Tell me."
Although he is much older than the one in front of him, there is a huge gap between the two in terms of knowledge and status.
There are only four academician-level giants in the entire Wuli University. Although he has met and communicated with them, this is the first time that such an academician giant has become his immediate boss.
And this is still in a private enterprise, not a school. The leader has greater rights over his subordinates, and the pressure on him is greater.
Of course, if you seize the opportunity, especially if the Chuanhai Institute of Materials has just begun to expand, the future will be bright.
He is almost fifty this year, and his academic level is there. Although it is not weak, it is not top-notch, so his prospects for promotion in Wuli have almost reached its peak.
And in a new environment, he might be able to go further. This is also the reason why he was poached, not only for money, but also for the hope of promotion.
Xu Chuan didn't pay much attention to these things. He connected the computer on his desk to the virtual projection and opened the research data on ultra-low-temperature superconducting copper-carbon-silver composite materials.
"I have some questions about the ultra-low-temperature superconducting copper-carbon-silver composite material you developed."
"The first is about the ray diffraction analysis data. Through ray studies, the sample has a structural phase transition process from orthorhombic to tetragonal at ≈0.04, and the unit cell volume becomes larger as the copper component increases."
"The zero resistance temperature measured by the r-t curve will decrease rapidly as the copper component increases. Until it drops below 0k, the zero resistance temperature will decrease with increase, and there will be no sudden change at the structural phase transition point."
"What do you think about this?"
There is no analytical answer to this question in the data Fan Pengyue gave him, which means that the current analysis results have not been produced.
If you want to know, the fastest way is to ask the person in charge of the experiment directly.
Song Wenbo thought for a while and said: "According to my speculation, this should be the effect of the doping of elements such as adhesives on copper-carbon-silver composite materials. The electronic doping of adhesives will cause its lattice coefficient to change.
Variety."
"I previously studied the effect of hole doping on the electronic structure when I was at Wuli University. Under external pressure, the magnetism of the system is gradually suppressed by the many-body effect of electrons in the strongly correlated system."
"This may be the reason why the zero resistance temperature decreases as the temperature decreases below 0k, and there is no sudden change at the structural phase transition point."
Listening to Song Wenbo's explanation, Xu Chuan tapped his fingers on the table one after another, and his mind fell into deep thought.
Does hole doping affect the electronic structure and lattice coefficient?
If he remembered correctly, when he was researching copper-carbon-silver composite superconducting materials in his previous life, what he initially studied was not copper-carbon-silver composite materials, but copper-silver oxide nanomaterials.
Because oxidized materials are recognized as the most promising to break through the limitations of high-temperature superconductivity.
The reason why he later replaced oxygen with carbon was actually due to an unexpected experimental accident.
The reason why oxide superconductors have become mainstream is not only because they can break the limitations of ultra-low-temperature superconductivity, but also because cuprate high-temperature superconductors also exhibit many strange properties.
For example, its superconducting phase has d-wave pairing symmetry, which is different from the -wave symmetry of conventional superconductors;
Another example is that the parent material has an antiferromagnetic mott insulating phase, and phenomena such as pseudogaps and Fermi arcs exist in the under-doped region.
Today, Song Wenbo's words gave him a new inspiration, and he might be able to get the answer to the key that he had never figured out before.
If the original copper-silver oxide nanomaterial is regarded as a superconductor, perhaps the accidental carbon doping into the original material may be the key to breaking the TC critical temperature.
Perhaps, he can find the superconducting formation mechanism of cuprate oxide high-temperature superconductors.
If successful, this will definitely be the biggest breakthrough in history for high-temperature superconducting materials!
And with this theory, he can naturally develop superconducting materials as quickly as possible.
But now he still needs more data and information to verify his thoughts!
p: Completing yesterday’s second chapter, please vote for me