Material Empire

The yttrium-barium-copper-oxygen superconducting material that Chen Zongze and the others are currently studying is called a copper-based supermaterial. The basic design idea of ​​this type of material is to dope other elements, such as yttrium, samarium, neodymium, etc., on the copper oxide matrix. As soon as the copper-based superconducting material came out, it quickly broke through the boiling point of liquid nitrogen of 77K, which triggered an upsurge in the application of superconductivity in the liquid nitrogen temperature zone.

However, the Achilles' heel of copper-based superconductors is that copper oxide is essentially a ceramic material, which lacks toughness and ductility, and has extremely poor mechanical properties. This weakness makes the preparation of copper-based superconducting materials quite difficult, especially when making them into wire or strip materials, other tough materials must be used as substrates.

In addition, although the maximum critical temperature of copper-based superconducting materials has reached 135K under normal pressure and 164K under high pressure, it is still far from the room temperature requirement of about 300K. Most importantly, scientists believe through theoretical research that 164K may be close to the highest theoretical upper limit of copper-based superconducting materials. In other words, don't look at the development of copper-based superconductivity in full swing, but if the ultimate goal is room temperature superconductivity, then copper-based materials can already be considered for sleep.

In addition to copper-based materials, scientists have also studied magnesium diboride and organic superconducting materials, but the progress is also very slow, especially failed to form a theoretical breakthrough. In the first few years of the 21st century, superconductivity research seems to have entered a dead end, and it is difficult to find a new direction.

At the beginning of 2008, Hideo Nishino's research group in Japan reported that 26K superconductivity was observed in fluorine-doped lanthanum oxide iron arsenic compounds. Chinese scientists who had explored new superconductors in similar structural systems earlier got the news and quickly used samarium Lanthanum, cerium, praseodymium, neodymium, gadolinium and other element replacement materials, broke through the Macmillan limit of 40K in just a few tens of days, thus opening the door to iron-based superconducting materials.

The discovery of iron-based superconducting materials is another revolutionary discovery in superconducting research. Although iron-based superconducting materials have not broken through the liquid nitrogen temperature zone of 77K until Qin Hai crossed, scientists believe that this is only a matter of time. Born from conductive materials.

Qin Hai is very familiar with this period of scientific history. Now that he has a chance to do it all over again, he will not refuse to give the honor of discovering iron-based superconducting materials to his family. Moreover, he hopes to be able to raise the critical temperature of iron-based superconductivity to room temperature in his own hands, so as to finally solve the century-old problem of room temperature superconductivity.

Hearing Qin Hai say the four words iron-based superconductivity, Tranquility frowned and said, Qin Hai, you made a big mistake this time. According to the BCS superconductivity theory, magnetic substances are impossible It has high-temperature superconductivity. Iron is a typical magnetic element, and when we design superconducting materials, we will try to avoid the existence of iron.

Qin Hai smiled and said: Who told you that the BCS superconducting theory must be correct? Or, who told you that there is only one superconducting mechanism in nature? I won't tell you how I think about this principle, but I can suggest that you try doping iron-arsenic compounds with different elements, and I suspect you can observe superconducting properties in them.

Within a few years after the concept of iron-based superconductivity was proposed, scientists have discovered hundreds of iron-based superconductors, and some people even estimate that the number of members of the iron-based superconductor family can reach more than 3,000. In this case, Qin Hai didn't have to directly tell Tranquility all the experimental ideas of later generations of Japanese. He only needed to point out this direction, and Tranquility would definitely hit one of them even if he hit by mistake.

It's strange, brother, why are you so confident? Qin Shan turned to look at her brother and asked curiously. When she was in middle school, she only knew that although this brother didn't go to high school, he was familiar with high school knowledge and could give her and Ning Ning a lot of precise guidance. After she went to university, she realized that her brother was far from being outstanding in his homework. He knew almost everything about the development trend of material technology, and he could make excellent articles just by giving you an idea. If the guidance in high school can be explained by studying seriously, the current scientific research guidance can only be described as unpredictable.

Fortunately, both Qin Shan and Ning Jing, under Qin Hai's subtle influence, have become somewhat numb to such miracles. Occasionally have doubts, but also because of the habit, and put this doubt behind. Regarding Qin Hai's advice, the common reaction of the two of them is to quickly record, and then work hard in the direction Qin Hai pointed out. They know that there will be big fish in this direction.

Iron-based superconductivity... Tranquility patted her forehead and said, Is this related to electron scattering on the hole-electron Fermi surface? Mr. Chen mentioned such a conjecture in an academic report. It’s just that you don’t have time to do experiments. Qin Hai, you didn’t think so after listening to Teacher Chen’s report, did you?”

Professor Chen is probably not the only one who has such conjectures. Qin Hai said with a smile. Qin Hai only knew what Tranquility was talking about, such as holes, Fermi noodles, etc., but he didn't know why. It's time to show off. He waved his hand and said, Don't make things difficult for me, a technical school student, about this kind of theoretical problem. You should hurry up and do experiments. If you have any theoretical problems, you can go to Teacher Chen to discuss them. However, you have to keep this idea a secret first. , if it leaks out and other people find out, you won’t be able to grab the originality.”

Didn't you ask us all to do applied research? How can I have time to do these experiments? Tranquility giggled and led Qin Hai into the army.

Qin Hai said seriously: Doing applied research is other people's business. After all, you are also the major shareholder of the research center. Do you still need to do such non-technical things?

If Zhang Shengying heard these words, he would probably spurt a mouthful of old blood three feet away. She is a big professor, and she is forced to do applied research, otherwise she will not be able to receive experimental materials. Tranquility, a first-year direct blogger, can actually enjoy the treatment of not having to do applications and concentrate on theory. Is there any reason in this world?

Tranquility obviously thought of this too, she said: I don't dare, the students should call me later.

Qin Haidao: It's not difficult. I'll just tell Teacher Chen and let him arrange for you to do this new direction. After the article is written, let Teacher Chen be the first author and you be the corresponding author. The benefits will be shared equally. He won't disagree.

If this experiment can really be done, it will completely subvert the traditional theory of superconductivity. There is really hope for such an article in Nature. If you tell Mr. Chen like this, he will definitely agree, and even put The strongest manpower is allocated to this direction. Tranquility said.

Qin Haidao: This is impossible. The honor of discovering iron-based superconductivity must be yours, and it cannot be taken away by others. Don't worry, it is not easy for others to steal it. The preparation of iron-based materials is much more difficult than copper-based materials, and the cost is much higher. It’s also much bigger, I don’t nod, others can’t get so much money for sample preparation, so you just go ahead and do it boldly, glory belongs to Tranquility, I’m optimistic about you.”

Tranquility said falsely: Since you are so sure, why don't you do it yourself? Don't you suffer a loss by giving me such a good idea?

Qin Shan pursed her lips and sneered: Xiao Jing, don't be hypocritical, my brother's is yours, why are you pretending in front of me?

Xiao Shan, you don't want to eat apples anymore, do you? Tranquility threatened Qin Hai while holding up a half-peeled apple.

Regarding the relationship between her and Qin Hai, whether it is Qin Shan, Qin Ling, or her own brother Ning Mo, they have been teased countless times in half-joking and half-serious ways, but Qin Hai, a big stick, has never let go. Excuse me, I really don't know what he was thinking.

In fact, Qin Hai had already been attracted by this beautiful and cheerful girl when he first met Tranquility, otherwise he would not have been clingy and unclear to Tranquility in the following years. Unclear. The key point is that, as a time traveler, Qin Hai was nearly 30 years old in his previous life. When he first saw Ning Jing, Ning Ning was only 16 years old.

It was such a psychological barrier that accompanied Qin Hai for many years. Till now, Tranquility has graduated from university, and the apple has turned attractive red, Qin Hai finally felt that he could accept this kind of temptation. A few days ago, when I went to the Superconducting Research Center, Brother Hou said that every day, many dandies driving luxury cars came to harass Ning Jing, which made Qin Hai feel a sense of crisis. What about when Tranquility confesses?

Xiaojing, Xiaoshan didn't say anything, I forgot about it. I heard from you senior brother Hou that there are quite a few people driving luxury cars to the research center to look for you in this period of time. What's going on? Qin Hai asked leisurely.

Tranquility blushed, took a sip, and said: Aren't they all local tyrants who think they are rich, many of them are seniors who graduated from our school in the past, and they didn't know how to hear my name, so they drove away They came to make friends with me. Some said they wanted to take me to dinner, some said they wanted to invite me to watch a movie, some of them were uncles in their 30s, and they didn’t think they were shabby.

By the way, there is another person who makes me laugh so hard, he is fatter than my elder brother, and he said to me that day: Junior Sister Ning, where can you find a talented young man like me?

Speaking of this, she stood up and gestured to the man's waistline, and then, together with Qin Shan, she laughed until she burst into tears.

Your circle is really chaotic... Qin Hai also commented with a smile, and then asked: Among these people, is there anyone you can take a fancy to?

What do you think? Tranquility stared at Qin Hai and asked, Do you really want me to find someone who can catch my eye among them?