This 35th volume of the 'Studies' is devoted to the technologically important BSCCO system. It focuses on a host of topics such as the synthesis and fabrication of conductors, superconducting BSCCO magnets, and the basic technological properties of the material in relation to the microstructure. The authors are distinguished in the field, working in different parts of the world, maintaining the international character of the series.
This Proceedings is a collection of papers presented at the Third Annual Conference on Superconductivity and Applications organized by the New York State Institute on Superconductivity. This year the Conference was held at the Buffalo Hilton Hotel on September 19- 21, 1989, with previous meetings on September 28-29,1987, and April 18-20, 1988. As in previous years, this meeting was highly successful, with an attendance of over three hundred researchers participating in lively scientific exchanges and discussions. The high quality of the talks is evident in this Proceedings. The field of high temperature superconductivity has matured considerably since its early days of media frenzy and rapid new discoveries. However, the enthusiasm and pace of research have not slowed down. A much better picture of the nature of high temperature superconductivity, the properties of these new materials and where they may find their eventual use has emerged. Processing techniques, especially thin film deposition, have been perfected nearly to the point of allowing commercial applications. We expect continued phenomenal growth of the field of high temperature superconductivity, both in terms of research and applications for many years to come.
This volume is based on the proceedings of the NATO-sponsored Advanced Studies Institute (ASn on The New Superconducting Electronics (held 9-20 August 1992 in Waterville Valley, New Hampshire USA). The contents herein are intended to provide an update to an earlier volume on the same subject (based on a NATO ASI held in 1988). Four years seems a relatively short time interval, and our title itself, featuring The New Superconducting Electronics, may appear somewhat pretentious. Nevertheless, we feel strongly that the ASI fostered a timely reexamination of the technical progress and application potential of this rapid-paced field. There are, indeed, many new avenues for technological innovation which were not envisioned or considered possible four years ago. The greatest advances by far have occurred with regard to oxide superconductors, the so-called high transition-temperature superconductors, known in short as HTS. These advances are mainly in the ability to fabricate both (1) high-quality, relatively large-area films for microwave filters and (2) multilayer device structures, principally superconducting-normal-superconducting (SNS) Josephson junctions, for superconducting-quantum-interference-device (SQUID) magnetometers. Additionally, we have seen the invention and development of the flux-flow transistor, a planar three-terminal device. During the earlier ASI only the very first HTS films with adequate critical-current density had just been fabricated, and these were of limited area and had high resistance for microwave current.
This symposium focused on new superconductors, electronics, magnet technology, energy and new applications. Recent discoveries in HTc, with transition temperatures over 90 K, have spawned a search for practical new applications. These applications extend from current uses such as that of the medical MRI to future applications, represented by research on new high-temperature materials. They span from microcircuit applications to the proposed SMES and fusion reactor applications.
Glassy Bi-Sr-Ca-Cu-O (BSCCO) precursors were prepared by different melt-quenching methods to investigate the melt properties of the BSCCO system before the crystallization investigations were started. In order to fabricate superconductors having high critical temperature and current density using the glass-ceramic route, it is necessary to clarify the total chemical composition of the quenched precursor. For the first time the total chemical composition of such precursors has been directly measured by the direct element analysis and correlated with the taken process steps. The results from the element analysis demonstrated significant chemical deviations in composition with respect to the starting composition and strong chemical inhomogeneities of the sample. The crystallization dependence was investigated on numerous parameters for the BSCCO system such as initial composition, atmosphere, Sr:Ca ratio, average valence state of the glassy precursor and the dependence of Bi substitution by Pb. It could be demonstrated that the copper valence dependence on the phase formation and crystallization of the high-TC phase plays an important role in the BSCCO system. It could also be demonstrated that the smallest chemical deviation could strongly influence the phase formation in dependence of melt temperature, influencing not only the average copper valence but also the different cation concentrations. From literature there are barely any results or conclusions drawn of the chemical composition of the quenched glassy precursors that however is critical to control the crystallization behavior and understanding the influences on the superconductive properties as demonstrated in this work.
This is an advanced textbook for graduate students and researchers wishing to learn about high temperature superconductivity in copper oxides, in particular the Kamimura-Suwa (K-S) model. Because a number of models have been proposed since the discovery of high temperature superconductivity by Bednorz and Müller in 1986, the book first explains briefly the historical development that led to the K-S model. It then focuses on the physical background necessary to understand the K-S model and on the basic principles behind various physical phenomena such as electronic structures, electrical, thermal and optical properties, and the mechanism of high temperature superconductivity.
