Superconductivity超导性
If mercury is cooled below 4.1 K, it loses all electric resistance. This discovery of superconductivity by H. Kammerlingh Onnes in 1911 was followed by the observation of other metals which exhibit zero resistivity below a certain critical temperature. The fact that the resistance is zero has been demonstrated by sustaining currents in superconducting lead rings for many years with no measurable reduction. An induced current in an ordinary metal ring would decay rapidly from the dissipation of ordinary resistance, but superconducting rings had exhibited a decay constant of over a billion years! 如果水银被冷却到4.1 K以下，它将失去所有电电阻。1911年，H. Kammerlingh Onnes发现超导性，这一发现随后观察到其他金属在一定临界温度以下表现出零电阻性。零电阻的事实已通过在超导铅环中维持电流多年而得到证实，没有可测量的电阻减少。在普通金属环中，感应电流会因普通电阻的耗散而迅速衰减，但超导环却表现出超过十亿年的衰减常数！
One of the properties of a superconductor is that it will exclude magnetic fields, a phenomenon called the Meissner effect. 超导体的一个特性是它会排斥磁场，这种现象称为迈斯纳效应。
The disappearance of electrical resistivity was modeled in terms of electron pairing in the crystal lattice by John Bardeen, Leon Cooper, and Robert Schrieffer in what is commonly called the BCS theory. 约翰·巴里顿、伦·科珀和罗伯特·施里弗用晶体晶格中的电子成对来解释电导率的消失，这一理论通常称为BCS理论。
A new era in the study of superconductivity began in 1986 with the discovery of high critical temperature superconductors. 超导性研究进入了一个新时代，这一新时代始于1986年高温超导体的发现。
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Index Superconductivity concepts 索引 超导概念 | ||
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Critical Temperature for Superconductors超导体的临界温度
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Index Superconductivity concepts Reference Rohlf,Ch 15 索引 超导概念 参考 Rohlf，第15章 | ||||||||||||||||||||||||||
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Types I and II SuperconductorsI型和II型超导体
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. 有三十种纯金属在低温下表现出零电阻，并具有将磁场排斥出超导体（迈斯纳效应）的性质。它们被称为一类超导体。超导性仅在它们的临界温度和临界磁场强度以下存在。一类超导体 well described by the BCS theory.
Starting in 1930 with lead-bismuth alloys, a number of alloys were found which exhibited superconductivity; they are called Type II superconductors. They were found to have much higher critical fields and therefore could carry much higher current densities while remaining in the superconducting state. 从1930年开始，以铅-铋合金为起点，人们发现了一些表现出超导性的合金；这些被称为II型超导体。它们被发现具有更高的临界磁场，因此在保持超导状态的同时可以承载更高的电流密度。
The variations on barium-copper-oxide ceramics which achieved the superconducting state at much higher temperatures are often just referred to as high temperature superconductors and form a class of their own. 在较高温度下实现超导态的钡铜氧化物陶瓷的变种通常被称为高温超导体，属于一个独立的类别。
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Type I Superconductors一类超导体
The 27 pure metals listed in the table below 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. 表下面列出的27种纯金属被称为Ⅰ型超导体。其特征是临界温度以下的电阻率为零，内部磁场为零（迈斯纳效应），以及当磁场超过临界磁场时超导性将消失。
*Gd at Tc=1.1 is questionable. Source is Rohlf, Ch 15, but this may be a misprint. Ga has Tc about 1.1, so Ga value may have been attributed to Gd. *Gd 在 Tc =1.1 时的值存疑。来源是 Rohlf 第15章，但可能为笔误。Ga 的 Tc 约为 1.1，因此可能将 Ga 的值误归于 Gd。
**"Superconductivity of Hexagonal Beryllium'" R.L. Falge Jr., Physics Letters A 24 1967.
六方氧化铍的超导性' R.L. Falge Jr., Physics Letters A 24 1967. |
Index Superconductivity concepts Reference Rohlf Ch 15 索引 超导概念 参考 Rohlf 第15章 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Type II SuperconductorsII型超导体
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Index Superconductivity concepts Reference: Blatt, Modern Physics 索引 超导概念 参考文献：Blatt，现代物理 | ||||||||||||||||||||||||||||||||||
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