Superconductors are materials that have zero electrical resistance and can be used to create extremely powerful magnets. They are also able to levitate above magnetic surfaces, making them an important technology for a variety of applications.
The first superconductor was discovered in 1911 by Dutch physicist Heike Kamerlingh Onnes. Since then, many different types of superconductors have been found and studied. The most widely known type of superconductor is made from niobium-titanium (NbTi) wire. This material can carry up to 200 times more current than copper wire of the same size, making it ideal for use in electric power grids and maglev trains.
Other types of superconductors include those made from iron (Fe), lead (Pb), mercury (Hg), yttrium barium copper oxide (YBCO), and thallium oxide (Tl2O3). These materials have critical temperatures ranging from 2 Kelvin (-271°C) to over 100 Kelvin (-173°C). YBCO is the highest temperature superconductor currently known, with a critical temperature of around -135°C.
Superconductivity occurs when electrons pair up and “cooperate” with each other instead of moving independently like they do in normal conductor materials. The pairs are held together by a force called the electron-phonon interaction. This force is created by vibrations in the lattice structure of the material caused by the movement of electrons through it. At high temperatures, this interaction is too weak to keep the electrons paired up, but at low temperatures it becomes strong enough to overcome thermal energy effects and allow pairs to form.
Once formed, these electron pairs can move freely through the lattice without being scattered or deflected by impurities or imperfections present in the material. This allows electric current to flow freely without resistance, leading to zero electrical resistance in the material as a whole. In addition, these moving electron pairs generate a magnetic field called the Meissner effect which expels any external magnetic fields from inside the superconductor completely .