Most materials people use are insulators, like plastic, or conductors, like an aluminum pot or a copper cable. Insulators show very high resistance to electricity. Conductors like copper show some resistance. Another class of materials show no resistance at all when cooled to very low temperatures, cooler than the coolest deep freezer. Called superconductors, they were discovered in 1911. Today, they are revolutionizing the electric grid, cell phone technology and medical diagnosis. Scientists are working to make them perform at room temperature.Some of the technological applications of superconductivity include:
1. the production of sensitive magnetometers based on SQUIDs
2. fast digital circuits (including those based on Josephson junctions and rapid single flux quantum technology),
3. powerful superconducting electromagnets used in maglev trains, magnetic confinement fusion reactors (e.g. tokamaks), and magnets used in particle accelerators
4. low-loss power cables
But there are disadvantages. Superconducting materials superconduct only when kept below a given temperature called the transition temperature. For presently known practical superconductors, keeping them below that temperature involves a lot of expensive cryogenic technology. Thus, superconductors still do not show up in most everyday electronics. Scientists are working on designing superconductors that can operate at room temperature.
2 advantages In relative detail:
Transforming the Electricity Grid The electric power grid is among the greatest engineering achievements of the 20th century. Demand, however, is much more than supply. Superconductor technology provides loss-less wires and cables and improves the reliability and efficiency of the power grid. Plans are underway to replace by 2030 the present power grid with a superconducting power grid. A superconducting power system occupies less real estate and is buried in the ground, quite different from present day grid lines. It saves power and with it the financial savings and the environmental benefits also accrue
2. One of the first large-scale applications of superconductivity is in medical diagnosis. Magnetic resonance imaging, or MRI, uses powerful superconducting magnets to produce large and uniform magnetic fields inside the patient's body.
Recent breakthrough in India
Two scientists of India from the Indian Institute of Science (IISc), Bengaluru, posted their experimental findings that had claimed that they had found superconductivity at room-temperature and pressure in a nanostructure composite of gold and silver. Both these noble metals, which are good conductors, are individually known not to become superconductors even at temperatures approaching absolute zero (-273.15º C).The process used by them is as follows. Silver nanoparticles about 1 nm wide, prepared by “standard colloidal techniques”, were embedded in a gold matrix in a chemical sintering process. The nano strucured gold-silver composite globules so obtained were about 10-20 nm in size. These were then turned into thin films and pellets for electrical resistivity and magnetic susceptibility measurements respectively.