proposed in 1957 by John Bardeen (1908-1991), Leon Cooper, and John Schrieffer. It came to be known as the BCS theory. Superconductivity was independently explained by Nikolay Bogolyubov (1909-1992). The BCS theory explained the superconducting current as a superfluid of "Cooper pairs" – pairs of electrons interacting through the exchange of phonons. For this work, the authors were awarded the Nobel Prize in 1972. In 1959 Lev Gor'kov showed that the BCS theory becomes equivalent to the Ginzburg-Landau theory close to the critical temperature.
Generalizations of these theories form the basis for understanding the closely related phenomenon of (because they fall into the Lambda transition universality class), but the extent to which similar generalizations can be applied to unconventional superconductors is still controversial.
In 1962 the first commercial superconducting wire, a - alloy, was developed by researchers at Westinghouse Electric Corporation. In the same year, Brian Josephson made the important theoretical prediction that a supercurrent can flow between two pieces of superconductor separated by a thin layer of insulator. This phenomenon, now called the "Josephson effect," is exploited by superconducting devices such as SQUIDs (superconducting quantum interference devices). Josephson was awarded the Nobel Prize for this work in 1973.
Until 1986, physicists had believed that the BCS theory forbade superconductivity at temperatures above about 30 K. That year, however, Johannes Bednorz and Karl Müller discovered superconductivity in a -based cuprate perovskite material, which had a transition temperature of 35 K (Nobel Prize in Physics, 1987). It was soon found by Paul C. W. Chu of the University of Houston and M. K. Wu at the University of Alabama in Huntsville that replacing the lanthanum with (to make YBCO) raised the critical temperature to 92 K. This latter discovery was significant because liquid nitrogen could then be used as a refrigerant (at atmospheric pressure, the boiling point of nitrogen is 77 K). This is important commercially because liquid nitrogen can be produced cheaply on-site with no raw materials, and is not prone to some of the problems (such as solid air plugs) of liquid helium in piping. Many other cuprate superconductors have since been discovered, and the theory of superconductivity in these materials is one of the major outstanding challenges of theoretical condensed matter physics.
Answer the questions.
1. When did superconductivity discover?
2. What kinds of properties are called superconductors?
3. What are superconductors used for?
4. Where does superconductivity occur?
5. Who was awarded by the Nobel Prize in Physics in 1913?
Put in a/an or the where necessary.
1. In 1950, James Maxwell and Reynolds et al. found that ___ critical temperature of __superconductor depends on ___ of ___constituent . 2. In 1962 ___ first commercial superconducting wire, ___ - alloy, was developed by researchers at Westinghouse Electric Corporation. 3. Brian Josephson made ___ important theoretical prediction that ___ supercurrent can flow between two pieces of superconductor separated by __thin layer of insulator. 4. Josephson was awarded ___Nobel Prize for this work in 1973. 5. Johannes Bednorz and Karl Müller discovered superconductivity in __-based cuprate perovskite material, which had __transition temperature of 35 K (Nobel Prize in Physics, 1987).
Put the verb into the correct form.
1. The of a metallic ____gradually as the temperature is lowered.( decrease) 2. The resistance of a superconductor, on the other hand, ___abruptly to zero when the material is cooled below a temperature called its "critical temperature". (drop) 3. Superconductivity _____in a wide variety of materials, including simple elements like and , various metallic , and certain kinds of ceramic materials. (occur) 4. In 1986, the discovery of HTS, with critical temperatures in excess of 90 K, ____interest and research in superconductivity for several reasons. (renew) 5.The next important step in understanding superconductivity ____in 1933, when Walter Meissner and Robert Ochsenfeld ____ that superconductors ___magnetic fields.(occurr/discover/ apply)
Put the verb into the most suitable passive form.
1.Superconductivity ____ in 1911 by and _____by exactly zero and exclusion of the interior .
(discover/ characterize) 2. Superconductors ____to make some of the most powerful electromagnets known to man, including those used in MRI machines. (use) 3.They ___also ___to make digital circuits, highly sensitive magnetometers, and filters for mobile phone base stations. (use) 4. They ___also for the separation of weakly magnetic particles from less magnetic or nonmagnetic particles. (can use) 5. Superconductivity does not occur in noble metals like and , nor in most metals that ___spontaneously.(can/ magnetize). 6. ____the in 1913. (award)
Put in a preposition where necessary.
1. Superconductivity was discovered __1911 __ , who was studying the resistance __ solid __ cryogenic temperatures using the recently discovered liquid as a refrigerant. 2. ___1950 Lev Landau and Vitaly Ginzburg formulated what came to be called the phenomenological Ginzburg-Landau theory ___superconductivity. 3. The discovery revealed that the internal mechanism responsible ___ superconductivity was related __ the attractive force ____electrons and the ion lattice beneath. 4. The complete, microscopic theory ___ superconductivity was finally proposed ___ 1957 __John Bardeen (1908-1991), Leon Cooper, and John Schrieffer.5. ___ 1959 Lev Gor'kov showed that the BCS theory becomes equivalent ___ the Ginzburg-Landau theory close __ the critical temperature.
Put the verb into the correct form. Use gerund or the infinitive
1. ____ future applications include high-performance , power storage devices, electric power transmission, . (promise) 2. Superconductivity occurs in a wide variety of materials, _____simple elements like and , various metallic , and certain kinds of ceramic materials known as high-temperature superconductors. ( include) 3. It ____be known as the BCS theory. (come) 4. This theory had great success in ____the macroscopic properties of superconductors. (explain) 5. Generalizations of these theories form the basis for____ the closely related phenomenon of .
