Superconductors Type I |
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| There are thirty pure metals which exhibit zero resistivity at low temperatures and have the property of excluding magnetic fields from the interior of the superconductor (Meissner effect). They are called Type I superconductors. The superconductivity exists only below their critical temperatures and below a critical magnetic field strength. Type I superconductors are well described by the BCS theory. | ||||
| The thirty pure metals listed at
right are called Type I superconductors. The identifying
characteristics are zero electrical resistivity below a
critical temperature, zero internal magnetic field (Meissner
effect), and a critical magnetic field above which
superconductivity ceases. The superconductivity in Type I superconductors is modeled well by the BCS theory which relies upon electron pairs coupled by lattice vibration interactions. Remarkably, the best conductors at room temperature (gold, silver, and copper) do not become superconducting at all. They have the smallest lattice vibrations, so their behavior correlates well with the BCS Theory. While instructive for understanding superconductivity, the Type I superconductors have been of limited practical usefulness because the critical magnetic fields are so small and the superconducting state disappears suddenly at that temperature. Type I superconductors are sometimes called "soft" superconductors while the Type II are "hard", maintaining the superconducting state to higher temperatures and magnetic fields. Such as : Be, Rh, W, Ir, ... |
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http://hyperphysics.phy-astr.gsu.edu/hbase/solids/scond.html |
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