High-Temperature Superconductors

The discovery by J. G. Bednorz and K. A. Mtllier in 1986 that the superconducting state can exist in oxides at temperatures above 30 K stimulated research in the field of superconductivity and opened up a new field of research. Within a few years a large number of cuprate superconductors with transition temperatures well above the boiling point of liquid nitrogen have been found. The possibility of using liquid nitrogen as coolant re-stimulated interest in power applications of supercon­ ductivity. In this book an overview of the known high-Te superconductors and their physical properties is presented. Aspects related to conductor fabrication and high-current applications are emphasised. The material should be suitable for use in graduate­ level courses on superconductivity. Researchers in the field may profit from the large number of tables and references describing its status at the end of 1997. An introduction to high-To superconductivity must be based on the fundamental physical principles of normal-state electrical conductivity and the well-known characteristics of conventional superconductors. In Chapter 2 this background is provided. Crystal structures, anisotropic properties and general trends of the critical temperatures of the cuprate superconductors are described in Chapters 3 and 4. The processing of superconductor powders addressed in Chapter 5 affects considerably the current-carrying capacity of high-T. wires. In Chapter 6 several fabrication techniques for superconducting wires are described. In addition, the factors limiting the transport critical currents ofhigh-Te wires are discussed.