From Quantum Paraelectric Ferroelectric Perovskite Oxides To High Temperature Superconducting Copper Oxides In Honor Of Professor K A M Uuml Ller For His Lifework

Superconductivity is the ability of certain materials to conduct electrical current with no resistance and extremely low losses. High temperature superconductors, such as La2-xSrxCuOx (Tc=40K) and YBa2Cu3O7-x (Tc=90K), were discovered in 1987 and have been actively studied since. In spite of an intense world-wide research, a complete understanding of the copper oxide (cuprate) materials is still lacking. Many fundamental questions are unanswered, particularly the mechanism by which high-Tc superconductivity occurs. More broadly, the cuprates are in a class of solids with strong electron-electron interactions. An understanding of such 'strongly correlated' solids is perhaps the major unsolved problem of condensed matter physics with over ten thousand researchers working on this topic. High-Tc superconductors also have significant potential for applications in technologies ranging from electric power generation and transmission to digital electronics. This ability to carry large amounts of current can be applied to electric power devices such as motors and generators, and to electricity transmission in power lines. For example, superconductors can carry as much as 100 times the amount of electricity of ordinary copper or aluminium wires of the same size. This Publication presents new research on yttrium barium copper oxide superconductors, often abbreviated YBCO, which is a chemical compound with the formula YBa2Cu3O7. This material, a famous 'high-temperature superconductor', achieved prominence because it was the first material to superconduct above the boiling point of nitrogen. All materials developed before YBCO became superconducting only at temperatures near the boiling points of liquid helium or liquid hydrogen (Tb = 20.1 K). The significance of the discovery of YBCO is the breakthrough in the refrigerant used to cool the material to below the critical temperature.

This study reviews the experimental aspects of oxide superconductivity, with transition temperatures from 30 K to above 100 K. It discusses experimental descriptions of principle superconducting compounds and covers VSC theory, electron-photon interaction and new theoretical models.

Superconductivity has been transformed into a rich field of intensive and highly competitive research, encompassing diverse disciplines such as structural chemistry, ceramic engineering, metallurgy, solid state electronics as well as experimental and theoretical condensed matter physics. The high temperature superconductors (HTSCs) discovered are from the family of ceramic oxides. Their large scale utilisation in electrical utilities and in microelectronic devices are challenges which can perhaps be effectively met only through consolidated efforts and expertise of a multidisciplinary nature. The growth of the new field has occurred on an international scale and perhaps has been more rapid than in most other fields. Each chapter in these volumes comprises a detailed review or an extended paper focussing on one or more of the aspects of research and applications, including state-of-art technology pertaining to HTSCs.

Superconductivity is the ability of certain materials to conduct electrical current with no resistance and extremely low losses. High temperature superconductors, such as La2-xSrxCuOx (Tc=40K) and YBa2Cu3O7-x (Tc=90K), were discovered in 1987 and have been actively studied since. In spite of an intense world-wide research, a complete understanding of the copper oxide (cuprate) materials is still lacking. Many fundamental questions are unanswered, particularly the mechanism by which high-Tc superconductivity occurs. More broadly, the cuprates are in a class of solids with strong electron-electron interactions. An understanding of such 'strongly correlated' solids is perhaps the major unsolved problem of condensed matter physics with over ten thousand researchers working on this topic. High-Tc superconductors also have significant potential for applications in technologies ranging from electric power generation and transmission to digital electronics. This ability to carry large amounts of current can be applied to electric power devices such as motors and generators, and to electricity transmission in power lines. For example, superconductors can carry as much as 100 times the amount of electricity of ordinary copper or aluminium wires of the same size. This Publication presents new research on yttrium barium copper oxide superconductors, often abbreviated YBCO, which is a chemical compound with the formula YBa2Cu3O7. This material, a famous 'high-temperature superconductor', achieved prominence because it was the first material to superconduct above the boiling point of nitrogen. All materials developed before YBCO became superconducting only at temperatures near the boiling points of liquid helium or liquid hydrogen (Tb = 20.1 K). The significance of the discovery of YBCO is the breakthrough in the refrigerant used to cool the material to below the critical temperature.

This book is a collection of proceedings of a symposium organized by the North Carolina Section of the American Chemical Society on the preparations, properties, and processing of high-temperature superconducting materials. The proceedings include papers of new results presented at the symposium.

The recent discovery of high-temperature superconductivity in copper based oxides is an event of major importance not only with respect to the physical phenomenon itself but also because it definitely shows that solid state chemistry, and especially the crystal chemistry of oxides, has a crucial place in the synthesis and understanding of new materials for future appli cations. The numerous papers published in the field of high Tc supercon ductors in the last five years demonstrate that the great complexity of these materials necessitates a close collaboration between physicists and solid state chemists. This book is based to a large extent on our experience of the crystal chemistry of copper oxides, which we have been studying in the laboratory for more than twelve years, but it also summarizes the main results which have been obtained for these compounds in the last five years relating to their spectacular superconducting properties. We have focused on the struc ture, chemical bonding and nonstoichiometry of these materials, bearing in mind that redox reactions are the key to the optimization of their supercon ducting properties, owing to the importance of the mixed valence of copper and its Jahn-Teller effect. We have also drawn on studies of extended defects by high-resolution electron microscopy and on their creation by ir radiation effects.

This Proceedings is dedicated to the topic of high temperature superconductors. It consists of invited talks by experts on the current status and development of ceramic superconductors.

Research into high-Tc materials demands the co-operation of physicists, chemists and materials scientists to discover the best solutions to the most important challenges presented by the field. In the fifth annual Workshop on High Temperature Superconductors and Novel Inorganic Materials Engineering, the topic is extended beyond high-Tc superconductivity to include other advanced oxide materials, mainly colossal magnetoresistance materials, which are closely related to the ceramic superconductors. This book covers the synthesis, characterisation (both structural and physical) and engineering of this class of materials.