However, since the early 1980s, people have discovered new materials. This new material can form superconductors at a temperature closer to normal temperature. In order to obtain superconductors on the basis of these substances, various countries are conducting various studies. This material is different from traditional materials because it does not need a cooling system.
Superconducting phenomenon was discovered by Heck Kamerling Agnes (1853- 1926) in1year. For decades, no one can explain it. Half a century later, a convincing explanation appeared in theory, that is, the "BCS theory" announced by physicists john bardeen (one of the inventors of transistors), Leon Cooper and John schrieffer in 1957. Electric current is a kind of free electron that flows around metal ions, that is, atoms with extra positive charges. The reason of resistance is that ions hinder the flow of electrons, which is caused by the thermal vibration of atoms themselves and the uncertainty of spatial position.
In superconductors, electrons combine in pairs to form so-called "Cooper pairs", and each Cooper pair exists as a single particle. These particles flow together, regardless of the resistance of metal ions, as if they were liquids. In this way, any potential resistance factors are actually neutralized.
What happens to ordinary conductors?
The above picture visualizes the concept of electrical conduction, just like the movement of a sphere (electron). It flows on an inclined plane (the inclined plane is equivalent to a conductor). Obstacles represent the irregular network structure of metal ions, and they do not allow electrons to flow freely. This is the reason for the formation of resistance. Electrons collide with total ions, output part of energy, and then convert it into heat.
What will happen to superconductors
Electrons in superconductors gather together in so-called Cooper pairs, and they behave as single particles, which is the same reason that gas molecules can gather into liquids. Superconducting electrons are expressed in liquid form as a whole. Although there are obstacles caused by the swing of metal ions and the irregularity of metal ion network, they can still flow freely without being affected.
superconductor
Superconductors and gas liquefaction are one of the hot topics in physics in the19th century. 19 1 1 year, Agnes found that the resistance of mercury dropped sharply at a low temperature of about 42K, so that it disappeared completely (that is, the resistance was zero). 19 13 He used the word "superconductivity" to express this phenomenon for the first time in a paper. Agnes won the 19 13 Nobel Prize in Physics for her achievements in studying the properties of matter and liquefied helium at low temperature.
It was not until 50 years later that people made a breakthrough. BCS theory marks the beginning of the modern stage of superconducting theory. BCS theory was first put forward by American physicists Badin, Cooper and schrieffer in 1957, and was named after the first capital letters of the three scientists. The core of this theory is to calculate the existence of * * vibration dynamics in superconductors, that is, the existence of "electron pairs".
From 65438 to 0962, Josephson, a graduate student at Cambridge University in England, predicted according to BCS theory that there would be a current between two superconducting materials separated by a thin insulating layer, that is, an "electron pair" could pass through the thin insulating layer (tunneling effect); At the same time, there are some special phenomena, such as the current passing through the thin insulation layer without applying voltage. If a voltage is applied, the current will stop and generate high-frequency oscillation. This superconducting physical phenomenon is called "Josephson effect". This effect has been confirmed in bell laboratory. Josephson effect strongly supports BCS theory. Therefore, Badin, Coopa and schrieffer won the 1972 Nobel Prize in Physics. Josephson won the 1973 Nobel Prize in Physics.
German physicist Bernoz and Swiss physicist Miao Lei began to concentrate on the superconductivity of rare earth oxides from 1983. 1986, they finally found an oxide material whose superconducting transition temperature was 12 degrees higher than that of previous superconducting materials. This discovery led to a major breakthrough in superconducting research. Scientists in the United States, China, Japan and other countries devoted themselves to research, and soon found ceramic materials with superconductivity in the temperature range of liquid nitrogen (below-196C), and then found superconducting materials with high critical temperature. This provides conditions for the application of superconductivity. Panoz and Miao Lei also won the 1987 Nobel Prize in Physics.
Superconductors are dominant.
Ke baotai
The most important feature of superconductors is that the resistance is zero when current passes through them. There are some types of metals (especially titanium, vanadium, chromium, iron and nickel). When they are placed at a particularly low temperature, the resistance of current passing through them is zero. In ordinary conductors, most of the current passing through the conductor becomes heat energy due to resistance, so it is "consumed". In superconductors, there is actually no resistance, so once the current is connected, it will never be interrupted in theory. In a circuit composed of electromagnets made of superconductors (coils, which generate electromagnetic fields when current passes through), theoretically only one current is fed, so that the electromagnetic fields can continue. Of course, it is actually lossy, so it is impossible to realize this kind of "perpetual motion machine". We have to consider the necessary energy input so that the superconductor can maintain the bottom temperature state (that is, -269℃, 4℃ higher than absolute zero) required to produce zero resistance phenomenon.
However, since the early 1980s, people have discovered new materials. This new material can form superconductors at a temperature closer to normal temperature. In order to obtain superconductors on the basis of these substances, various countries are conducting various studies. This material is different from traditional materials because it does not need a cooling system.
Superconducting phenomenon was discovered by Heck Kamerling Agnes (1853- 1926) in1year. For decades, no one can explain it. Half a century later, a convincing explanation appeared in theory, that is, the "BCS theory" announced by physicists john bardeen (one of the inventors of transistors), Leon Cooper and John schrieffer in 1957. Electric current is a kind of free electron that flows around metal ions, that is, atoms with extra positive charges. The reason of resistance is that ions hinder the flow of electrons, which is caused by the thermal vibration of atoms themselves and the uncertainty of spatial position.
In superconductors, electrons combine in pairs to form so-called "Cooper pairs", and each Cooper pair exists as a single particle. These particles flow together, regardless of the resistance of metal ions, as if they were liquids. In this way, any potential resistance factors are actually neutralized.
What happens to ordinary conductors?
The above picture visualizes the concept of electrical conduction, just like the movement of a sphere (electron). It flows on an inclined plane (the inclined plane is equivalent to a conductor). Obstacles represent the irregular network structure of metal ions, and they do not allow electrons to flow freely. This is the reason for the formation of resistance. Electrons collide with total ions, outputting part of energy, and then converting it into heat energy.
What will happen to superconductors
Electrons in superconductors gather together in so-called Cooper pairs, and they behave as single particles, which is the same reason that gas molecules can gather into liquids. Superconducting electrons are expressed in liquid form as a whole. Although there are obstacles caused by the swing of metal ions and the irregularity of metal ion network, they can still flow freely without being affected.
It has long been known that the resistance of metals will decrease with the decrease of temperature, but it is unknown to what extent the resistance will decrease when the temperature is close to absolute zero. In order to find out this problem, Dutch physicist Anis (1853 ~ 1926) began to study metal resistance at extremely low temperature. 19 1 1 year, when he measured the resistance of mercury at low temperature, he found that the resistance of mercury did not decrease with the decrease of temperature as expected, but suddenly disappeared completely when the temperature dropped to about -269℃. Later, it was found that some metals or alloys, when the temperature drops to a certain temperature, the resistance will also become zero. This phenomenon is called superconductivity, and substances that can be superconductive are called superconductors. The temperature at which the resistance of a substance becomes zero is called the superconducting transition temperature or superconducting critical temperature of the substance, which is expressed by TC. A substance has superconductivity below TC and loses superconductivity above TC.
The discovery of superconductors is of great significance in science and technology. For example, due to the development of modern production, the demand for electric energy has increased rapidly. According to statistics, the demand for electric energy will double almost every 10 year. However, the transmission line is resistive, and due to the thermal effect of current, the loss of electric energy on the transmission circuit is about more than. If we can find superconducting materials at room temperature, we can make large-scale use of superconducting properties in power generation, transmission and motors, which will cause great changes in various fields of modern technology. Therefore, the study of room temperature superconductors is an important topic at present. Even if there is no room temperature superconductor, it is of great significance to find superconductors with higher transition temperature. In this respect, China's research work is in the forefront of the world. Superconducting materials with TC of-14 1℃ were found in 1989, which is a major breakthrough in the research of high critical temperature superconductors.