The obvious application of superconducting materials is in the form of wires, and this has been the subject of much materials research effort. However, it is also possible to employ superconductors in bulk form. Just as superconductors in wire and tape form can replace conventional copper conductors, bulk superconductors can be used as replacements for rare-earth permanent magnets, but with trapped magnetic fields an order of magnitude larger. In addition, bulk superconductors can be used to provide passively stable magnetic levitation, by exploiting their flux pinning properties. It is this latter property which is often encountered in popular demonstrations of superconductivity, often coupled with an entirely incorrect explanation for stable levitation involving the Meissner effect.
In this summer school talk I will provide a broad overview of the materials science of bulk superconductors and key factors affecting their performance and suitability for applications. I will then review some of the key active areas of current research in the material science of bulk superconductors. My talk will conclude with a review of the applications of bulk superconductors, which range from the highly speculative, such as motors for long distance air travel, to the fully commercialised, such as bearings for high speed centrifuges.