11-07-2017, 09:39 AM
A superconductor is a material that can conduct electricity or carry electrons from one atom to another without resistance. This means that no heat, sound or any other form of energy will be released from the material when it has reached the "critical temperature" (Tc), or the temperature at which the material becomes superconducting. Unfortunately, most materials must be in an extremely low (very cold) state of energy to become superconductors. Research is underway to develop compounds that become superconductors at higher temperatures. At present, an excessive amount of energy must be used in the cooling process, which makes superconductors inefficient and uneconomical.
Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of fields of magnetic flux that occur in certain materials, called superconductors, when cooled below a characteristic critical temperature. It was discovered by the Dutch physicist Heike Kamerlingh Onnes on 8 April 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It is characterized by the Meissner effect, the complete expulsion of lines of magnetic field from the interior of the superconductor as it transits in the superconducting state. The appearance of the Meissner effect indicates that superconductivity can not be understood simply as the idealization of perfect conductivity in classical physics.
The electrical resistance of a metal conductor decreases gradually as the temperature drops. In ordinary conductors, such as copper or silver, this decrease is limited by impurities and other defects. Even near absolute zero, a real sample of a normal conductor shows some resistance. In a superconductor; The resistance drops abruptly to zero when the material cools below its critical temperature. An electric current flowing through a superconducting wire loop can persist indefinitely without power source.
In 1986, it was discovered that some cuprate-perovskite ceramic materials have a critical temperature above 90 K (-183 ° C). Such a high transition temperature is theoretically impossible for a conventional superconductor, leading to materials to be termed high temperature superconductors. The liquid nitrogen refrigerant available in scales boils at 77 K, and therefore superconducting at higher temperatures than this facilitates many experiments and applications that are less practical at lower temperatures.
Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of fields of magnetic flux that occur in certain materials, called superconductors, when cooled below a characteristic critical temperature. It was discovered by the Dutch physicist Heike Kamerlingh Onnes on 8 April 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It is characterized by the Meissner effect, the complete expulsion of lines of magnetic field from the interior of the superconductor as it transits in the superconducting state. The appearance of the Meissner effect indicates that superconductivity can not be understood simply as the idealization of perfect conductivity in classical physics.
The electrical resistance of a metal conductor decreases gradually as the temperature drops. In ordinary conductors, such as copper or silver, this decrease is limited by impurities and other defects. Even near absolute zero, a real sample of a normal conductor shows some resistance. In a superconductor; The resistance drops abruptly to zero when the material cools below its critical temperature. An electric current flowing through a superconducting wire loop can persist indefinitely without power source.
In 1986, it was discovered that some cuprate-perovskite ceramic materials have a critical temperature above 90 K (-183 ° C). Such a high transition temperature is theoretically impossible for a conventional superconductor, leading to materials to be termed high temperature superconductors. The liquid nitrogen refrigerant available in scales boils at 77 K, and therefore superconducting at higher temperatures than this facilitates many experiments and applications that are less practical at lower temperatures.