Materials science superconductivity

Superconductivity research has reached out to other branches of physics and materials science perhaps the strangest example of this is a study by Keusin-Elbaum... 

One of the most exciting developments in materials science in recent years involves mixed oxides containing rare earth metals. Some of these compounds are superconductors, as described in our Chemistry and Technology Box. Below a certain temperature, a superconductor can carry an immense electrical current without losses from resistance. Before 1986, it was thought that this property was limited to a few metals at temperatures below 25 K. Then it was found that a mixed oxide of lanthanum, barium, and copper showed superconductivity at around 30 K, and since then the temperature threshold for superconductivity has been advanced to 135 K. 

The importance of materials science to U.S. competitiveness can hardly be overstated. Key materials science areas underlie virtually every facet of modem life. Semiconductors underpin our electronics industry. Optical fibers are essential for communications. Superconducting materials will probably affect many areas ceramics, composites, and thin films are having a big impact now in transportation, construction, manufacturing, and even in sports—tennis rackets are an example. 

The first edition of this book published in 1986 was well received by the chemistry and materials science communities and this resulted in the paperback edition published in 1989. We are most gratified by this warm reception to the book which has been found useful by students and teachers as well as practising solid state chemists and materials scientists. Since we first wrote the book, there have been many new developments in the various aspects of solid state chemistry covering synthesis, structure elucidation, properties, phenomena and reactivity. The discovery of high-temperature superconductivity in the cuprates created a great sensation and gave a boost to the study of solid state chemistry. Many new types of materials such as the fullerenes and carbon nanotubes have been discovered. We have now revised the book taking into account the new developments so that it reflects the present status of the subject adequately and points to new directions. 

The search for new organic metals and superconductors has attracted a great deal of attention in synthetic chemistry and material science since the discovery of high electrical conductivity in conjugated polymers such as polyacetylene [1], Lots of theoretical studies have been carried out in order to understand the mechanism of conductivity and superconductivity in the conjugated polymers and related... 

Fig. 4.58 (a) Micrograph of lead section see text for details (b) Bi-2212 current leads the longer lengths are approx. 3x25x300 mm. (Courtesy of the IRC in Superconductivity and Department of Materials Science, University of Cambridge, UK, ABB Corporate Research, Switzerland and Advanced Ceramics Ltd., UK.)... 

Superconducting Materials Center, National Institute for Materials Science 1-1, Namiki, Tsukuba, Ibaraki 305-0044, Japan... 

The biggest explosion in materials chemistry and physics occurred in late 1986 when high-temperature superconductivity was discovered in a lanthanum cuprate, a material which was a ceramic and on which a few chemists had worked earlier. As stated in a report of the US National Academy of Sciences, this discovery changed the role of chemistry in the study of materials, and materials chemistry became a more significant part of materials science. It is around this time that even chemists started to consider solid state chemistry as an integral and important part of main-stream chemistry. 

A major scientific breakthrough in the area of material science involving copper occurred in late 1986 and early 1987 the discovery of the so-called high-temperature cuprate superconductors (see Superconductivity). These copper-oxide containing materials hold the record for the highest transition temperature (Tc, the temperature at which all resistance to electricity is lost), currently 133 K, which is sigiuficant... 

B.D. Merkle, R.N. Knisely, FA. Schmidt, and l.E. Anderson, Superconducting Yttrium Barium Copper Oxide (YBa CUjO ) Particulate Produced By Total Consumption Burner Processing, Materials Science and Engineering, V01.A124, No.l, 1990, pp.31-38. 

These are conductive, in some cases superconductive materials (such as K3C60 and Rb3C6o) and are of great interest in the field of materials science. These are principally ionic, rather than covalent compounds. The interested reader is encouraged to consult the reference below" for additional information about these compounds. 

The quest for superconductivity at always higher temperature has been a constant motivation in the material science research over the past quarter of the century. A well known example is the huge amount of work which has been invested in the synthesis, measurements and processing of intermetallic compounds belonging to the A-15 family of type II superconductors. These compounds V,Si [I] and NbjSn [2] are still at present the materials mostly used when superconductivity comes to applications [3]. 

Rubidium compounds are important in a number of areas of materials science, as catalysts for ammonia synthesis and oxidation of methane, as a component of some glasses and as a dopant metal in buckminsterfullerene (Ceo) causing it to become superconducting at 28 K. 

Many of the new tasks would be at the boundary with materials science. There are some that are obviously applications-oriented, like the electronic theory of high temperature superconduction in the layered copper-oxide perovskites, and other aspects of nanotechnology. There are also fundamental valence problems, such as accounting for the structures and properties of quasiciystals. Why is the association of transition metals and aluminium apparently of central importance How do we deal with the valence properties of systems where the free energy of formation or phase transition is dominated by the entropy term ... 

These instruments can address both fundamental and applied research problems. Whether one is trying to solve a device development riddle, understand the complicated vapor-phase thin-film growth process, or delve into the fundamental issues of the nature of superconductivity there is a configuration that can suit that problem. Materials science or physics, whatever the issue, structure or property or their relationship to each other, the SPM capabilities, high resolution, and ability to simultaneously measure structure and property make these instruments valuable additions to the electron microscope family. 

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