High-temperature superconductor illustration

Fig. 4.55 Tc against time illustrating the remarkable development following the discovery in 1986 of the high temperature superconductors. ( under pressure) (Adapted from Chu, C.W. (2000) High temperature superconducting materials present status, future challenges, and one recent example - the superconducting ferromagnet , Physica C, 341-348, 25-30.)...

A range of metals, alloys and metallic compounds are Type I superconductors (Table 28.1). However, to put the practical limitations of working with the materials listed in Table 28.1 (and others including the superconducting fullerides described in Section 14.4) into perspective, we must compare the values of with the boiling points of available coolants, e.g. liquid He (4.2 K), H2 (20.1 K) and N2 (77 K). The low values of limit the possible applications of these materials, and illustrate why the so-called high-temperature superconductors described below are more important than superconducting metals and alloys. 

A rather different approach from that given above will be found in Three theories of superconductivity by F. A. Matsen, J. Chem. Educ. (1987) 64, 842. The structural patterns associated with superconductivity are well illustrated in The Crystal Chemistry of High-Temperature Oxide Superconductors and Materials with Related Structures by H. Miiller-Buschbaum, Angew. Chem., Int. Ed. Engl. (1989) 28, 1472. A mixture of structure and some theory is to be found in a very readable, non-mathematical, article Some Structural-Electronic Aspects of High Temperature Superconductors , by J. K. Burdett, in Adv. Chem. Phys. (1993) 83, 207. 

Fig. 37.2 (A) Schematic illustration showing a conductive polymer/high-temperature superconductor sandwich device. To create such a structure, a YBa2Cu307-s thin film is deposited onto a MgO(lOO) substrate via laser ablation, a microbridge is patterned on the central portion of the film, and a conductive polymer layer is deposited electrochemi-cally onto the microbridge area. (B) Cyclic voltammetry (5 mV/s) recorded at room temperature in 0.1 M Et4NBp4/ acetonitrile for a YBa2Cu307-s thin-film electrode assembly coated with polypyrrole. Well-behaved voltammetry is observed, indicating that electronic charge flows readily between the superconductor and the polymer layer. (Adapted from Ref. 11.)...

As mentioned in Section 6.3, band waggoning in the early 1990s resulted in several proposals for uses of fullerene [30a] which until now have not reached fruition. High-temperature fullerene superconductors and a C60F60 lubricant illustrate the point. The latter, ball shaped perfluorinated hydrocarbon, should have revolutionized industry by minimizing friction losses of energy. The compound was synthesized. However, it proved unstable. Moreover, it... 

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