Magnesium diboride (MgB2) is an inexpensive and simple superconductor that can be synthesized by high temperature reaction between boron and magnesium (in the liquid or gaseous state). It was announced in the journalNature in March 2001. Its critical temperature (39 K) is the highest amongst conventional superconductors (phonon-mediated superconductors). This material was first synthesized in 1953 but its superconducting properties were not discovered until half a century later. Superconductivity is a phenomenon occurring in certain materials at low temperatures, characterised by the complete absence of electrical resistance and the damping of the interior magnetic field (the Meissner effect. ... A journal (through French from late Latin diurnalis, daily) is a daily record of events or business. ... The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ... Conventional superconductors are materials that display superconductivity as described by BCS theory or its extensions. ... In physics, a phonon is a quantized mode of vibration occurring in a rigid crystal lattice, such as the atomic lattice of a solid. ...
Though a conventional superconductor, it is a rather unusual one. Its electronic structure is such that there exist two types of electrons at the Fermi level with widely differing behaviours, one of them being much more strongly superconducting than the other. This is at odds with usual theories of phonon-mediated superconductivity which assume that all electrons behave in the same manner. For this reason, theoretical understanding of the properties of MgB2 is not yet achieved, particularly so in the presence of magnetic field. In quantum mechanics, particles with a half-integer spin, usually spin 1/2 (for example electrons) follow the Pauli exclusion principle, which states that no two particles may occupy the same quantum state. ... Current flowing through a wire produces a magnetic field (M) around the wire. ...
Less than six months after the metallic compound magnesiumdiboride was found to be a superconductor (April p11), scientists in the US have developed a practical technique for making wires from it.
Magnesiumdiboride has been a known substance since the 1950s, but it had never been tested for superconductivity.
The oxygen-tainted magnesiumdiboride films were able to work in magnetic fields almost twice as strong as those lacking the oxygen impurities.
This caused great excitement in the field as magnesiumdiboride is a much simpler material than many of the mixed oxides superconductors that have been produced that become superconducting at higher temperatures.
Magnesiumdiboride can be cooled with liquid neon, which is much more affordable then liquid helium and magnesiumdiboride is also cheaper than the niobium alloys used in MRI machines.
However, for magnesiumdiboride to be useful in MRI machines, it needs to be available in wire form, which posed the next problem for researchers, otherwise it would be no more useful then the exotic mixed oxides that researchers have produced in laboratories.
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