Superconducting materials applications

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Many of the ideas necessary to help describe and explain superconductivity involve topics you will encounter in future chemistry courses. Even armed with these ideas, however, researchers do not yet have a complete, accepted theory to explain this intriguing property. Nevertheless, the list of superconducting materials continues to expand, and engineers continue to find practical applications for them. 

In addition to catalytic applications, the perovskite backbone is a key component in modern high-temperature superconductive materials. By definition, a superconductor exhibits no resistance to electrical conductivity, and will oppose an external magnetic field, a phenomenon referred to as the Meissner effect (Figure 2.19). Many pure transition metals e.g., Ti, Zr, Hf, Mo, W, Ru, Os, Ir, Zn, Cd, Hg) and main group metals e.g., Al, Ga, In, Sn, Pb) exhibit superconductivity, many only when exposed to high-pressure conditions. These materials are referred to as Type I or soft superconductors. 

The superconducting component of an MRI system is, by far, the costliest part of the unit. It alone can set a hospital back at least 500,000. The machines, moreover, use around 80 percent of all of the superconducting material now sold—miles of niobium-titanium wire are wound into each magnet—making MRI one of today s few applications of superconductivity. 

Niobium alloys are used in superconducting materials. They are used in applications ranging from ma etic resonance imaging (MRI) to levitation trains, like the prototype pictured here. Such trains use ma etic levitation and are capable of reaching high speeds. IMAGE COPYRIGHT 2009, MARTIN TRAJKOVSKI. USED UNDER LICENSE FROM SHUTTERSTOCK.COM. 

An interesting application of thallium is in superconducting materials. Superconductors have no resistance to the flow of electricity. Once an electrical current begins flowing in the material, it continues to flow forever. Thallium is also used in wireless communications. 

Yttrium is often used to make alloys with other metals. An alloy is made by melting and mixing two or more metals. The mixture has properties different from those of the individual metals. Two of yttrium s most interesting applications are in lasers and superconducting materials. 

Van Tendeloo G, Ghose S, Amelinckx S (1989) A dynamical model for the P i-11 phase transition in anorthite, CaAl2Si20g I. Evidence from electron microscopy. Phys Chem Minerals 16 311-319 Van Tendeloo G, Zandbergen HW, Amelinckx S (1987) Electron diffraction and electron microscopic study of Ba-Y-Cu-0 superconducting materials. Sol Stat Comm 63 389-393 Veblen DR (1991) Polysomatism and polysomatic series A review and applications. Am Mineral 76 801-826... 

As discussed in Chapter 5, the conductivity of some compounds changes abruptly at a particular temperature. Below this critical temperature, they conduct with no appreciable resistance. These compounds are called superconductors. In the superconducting state, the compound offers no resistance to the flow of conducting species. A current started in a loop will therefore continue to flow indefinitely, without significant loss. This property, and others particularly associated with the superconducting state, could theoretically allow superconducting materials to be used for many applications, such as ... 

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