Superconductors are a special type of material that can conduct electric current almost without offering resistance, and therefore without producing an energy "loss". That is, metals are good conductors, both thermal and electrical, but these are heated when conducting a flow of electrons, because the atoms of the metal vibrate and collide with them. They offer resistance and energy is lost in the form of heat. This is sometimes not profitable.
There are several theories, models that help to better understand this phenomenon, but they are of great complexity.
As the temperature decreases, so does the resistance of the metal to electric current, so at temperatures around 0 K, some materials become superconductors. They can be various metals, if sufficiently cooled (some alloys, or even carbon compounds).
Materials are usually cooled with liquid helium, which is quite expensive. Therefore, "high temperature" superconductors are being investigated, which superconduct to temperatures as "high" as 77 K, and can be cooled with liquid nitrogen, much cheaper.
Classification
Superconductors can be classified according to several aspects, such as the materials that compose them (pure or alloys, carbon structures); the temperature at which they are superconductors (critical temperature), in high or low temperature superconductors. The most commonly used classification is according to their physical behaviour.
There are two types of superconductors:
Type I superconductors, which prevent magnetic fields from penetrating them, i.e. they shield them (Meissner effect). They are pure elements with a very low critical temperature.
Type II superconductors are "imperfect" superconductors that allow the magnetic fields to penetrate inside them, gradually passing from the superconducting state to the normal one. Among them are alloys, ceramic substances.
APPLICATIONS:
The applications of superconductors are very diverse, and, as these materials are still being researched, their utilities are expanding all the time. The lines of research focus on how to reduce the resistance of metals to the passage of electric current, at the highest possible temperature, in order to make them profitable.
Therefore, we are trying to find new materials.
The main applications are related to their magnetic properties, being used in fields as disparate as transport or medicine. When cooled and subjected to a magnetic field, they can levitate. Thus, it is used in high-speed trains, in countries like Japan, because this levitation avoids the rubbing with the tracks and allows an increase in speed (up to 550km/h!!!!). This is the case of the Shanghai Maglev train.
They are used in medicine, for nuclear magnetic resonances.
Also, in Energy Transport Systems. Being almost null the resistance that they exert, they would allow to transport electricity to great distances without this one dissipates in the environment in the form of heat.
They are even being tried to work with them for energy storage. They can also be used in medicine, for nuclear magnetic resonance, or in the study of molecules (nuclear magnetic resonance spectroscopy).
As with almost everything in today's science, this is a promising world that is expanding and has just begun, so its applications could reach almost unsuspected limits, if the research is adequate.
In addition, they can be used in particle accelerators.
All images were copied from pixabay
