High-Temperature Superconductors

Following the discovery of the oxide superconductors in 1986 by Bednorz and Müller, a number of new superconducting compounds was found exhibiting superconductivity above the liquid nitrogen temperature including rare-earth oxides and bismuth oxides, enabling cheaper cooling methods to be applied. The new class of superconducting materials featuring high critical temperatures (Tc above 77 K) and high second critical magnetic fields gave a new impetus to the research and development in superconductivity. Governments of many countries worldwide have encouraged scientists, engineers and industry to develop high temperature superconducting materials for practical use. Environmentally benign scenarios of high speed transport systems, energy saving by utilizing DC cables, medical equipment (e.g., magnetic resonance imaging (MRI) systems), a new class of magnetic drug delivery system (MDDS), nuclear magnetic resonance (NMR), and non-contact rotating machinery are expected. Nowadays, there is already a variety of high-Tc superconducting products available on the market, like single domain, batch processed bulks with diameters up to 140 mm, hundreds of kilometers of the first generation silver-sheathed Bi-2223 and Bi-2212 wires and tapes, and several kilometers of the second generation Y-123 tapes ('coated conductors') for winding coils of superconducting super-magnets or for constructing high-Tc super-cables for high energy transfer. The authors hope that, especially for young researchers, new upcoming engineers and students of superconductivity theory extension, the collected know-how in technology of superconducting thin films, wires, and bulks, and the new opportunities available for practical applications by the unique features of high-Tc materials will be very useful. The volume is designed to cover the recent achievements in occurrence, synthesis and application of high-Tc superconductors. The volume consists of a total of seventeen chapters, each of them defining in-depth the chapter subject and surveying recent developments in the field. The main objective of this volume is to summarize the recent advances in material science of high-Tc superconductors, including their properties, processing, and applications. New and challenging issues appear in this book, like superconducting large grain bulk RE-123, flux pinning, nanowire network fabrics and their applications, and a quantitative analysis on the normal-state Nernst coefficient. Furthermore, the book also covers recent developments on a variety of materials and the progress made, especially concerning the magnetic characterization of bulk C-doped MgB2, silver added bulk FeSe, and (BiPb)SrCaCuO systems, respectively. To show a full picture of the currently ongoing research efforts, the book covers large scale applications of bulk materials, including magnetic bearings, superconducting electric motors and their design layouts, hybrid-type superconducting magnetic bearings for rotating machinery, compact magnetic field generators, refrigerators, and recent developments in the application of superconducting super-magnets in the medical field. The authors would like to take this opportunity to express their sincere gratitude to all of the chapter contributors for their great endeavor in completing this book in time. They also wish to acknowledge Carra Feagaiga from NOVA Science Publisher for offering invaluable advice at every stage of editing this book. We would also like to extend our thanks to President Prof. M. Murakami-sensei, SIT for his constant support and encouragements. The team of authors and the editors sincerely hope that the presented ideas and information in this book will be helpful for interested readers, scientists, young researchers, bachelor and master students, and will encourage further development in the field.