Superconductive ceramics applications

The re arch in catalysis is still one of the driving forces for interface science. One can certainly add to the topics of interface physics the whole new field of interface problems that is about to spring out of the new high Tc superconducting ceramics, i.e. the fundamental problem of the matching of the superconducting carriers wave-functions with the normal state metal or semiconductor electron states, the super-conductor-superconductor interfaces and so on, as well as the wide open discovery field for devices and applications. 

A crucial concern in the application of superconducting ceramics is to devise ways to fabricate the new materials in desired shapes such as wires. This will be quite a challenge because these superconductors are ceramics and have the brittleness and fragility typical of ceramic materials. 

The Synthesis and Fabrication of Ceramics for Special Application 261 17.3.10. Preparation of Superconductive Ceramics 17.3.10.1. Low Temperature Superconductors... 

It should be pointed out that these methods have now been used far beyond the simple ionic systems where they began. For a discussion of some of these applications the reader should consult the chapters on superconducting ceramics (Chapter 10) and zeolites (Chapter 9). 

These applications do not even include superconducting ceramics, currently being developed for myriad applications. 

Part II deals with more recent processes and applications and functional and engineering ceramics. The engineering ceramics covered in this book were developed within the last decade. The functional ceramics covered include electro-ceramics, optoelectro-ceramics, superconductive ceramics, etc. 

Note that the issue of the brittleness of ceramics restricting their application is not limited to structural applications. For instance, the brittleness of superconducting ceramics had to be resolved by employing them either as thin films on ductile metal wires or embedded within ductile metal casings. Thus the understanding of how to defeat the brittleness of the ceramics impacts their use in a host of applications. 

I. K. Kaneto and K. Yoshino, The application of superconducting ceramics as substrates for the electrochemical deposition of conducting polymers and metals, Jpn. J, Appl. Phys. 26 L1842 (1987). 

Electrical and Electronic Applications. Silver neodecanoate [62804-19-7] has been used in the preparation of a capacitor-end termination composition (110), lead and stannous neodecanoate have been used in circuit-board fabrication (111), and stannous neodecanoate has been used to form patterned semiconductive tin oxide films (112). The silver salt has also been used in the preparation of ceramic superconductors (113). Neodecanoate salts of barium, copper, yttrium, and europium have been used to prepare superconducting films and patterned thin-fHm superconductors. To prepare these materials, the metal salts are deposited on a substrate, then decomposed by heat to give the thin film (114—116) or by a focused beam (electron, ion, or laser) to give the patterned thin film (117,118). The resulting films exhibit superconductivity above Hquid nitrogen temperatures. 

For a large number of applications involving ceramic materials, electrical conduction behavior is dorninant. In certain oxides, borides (see Boron compounds), nitrides (qv), and carbides (qv), metallic or fast ionic conduction may occur, making these materials useful in thick-film pastes, in fuel cell apphcations (see Fuel cells), or as electrodes for use over a wide temperature range. Superconductivity is also found in special ceramic oxides, and these materials are undergoing intensive research. Other classes of ceramic materials may behave as semiconductors (qv). These materials are used in many specialized apphcations including resistance heating elements and in devices such as rectifiers, photocells, varistors, and thermistors. 

Superconductivity The physical state in which all resistance to the flow of direct-current electricity disappears is defined as superconductivity. The Bardeen-Cooper-Schriefer (BCS) theoiy has been reasonably successful in accounting for most of the basic features observed of the superconducting state for low-temperature superconductors (LTS) operating below 23 K. The advent of the ceramic high-temperature superconductors (HTS) by Bednorz and Miller (Z. Phys. B64, 189, 1989) has called for modifications to existing theories which have not been finahzed to date. The massive interest in the new superconductors that can be cooled with liquid nitrogen is just now beginning to make its way into new applications. 

Recent applications of e-beam and HF-plasma SNMS have been published in the following areas aerosol particles [3.77], X-ray mirrors [3.78, 3.79], ceramics and hard coatings [3.80-3.84], glasses [3.85], interface reactions [3.86], ion implantations [3.87], molecular beam epitaxy (MBE) layers [3.88], multilayer systems [3.89], ohmic contacts [3.90], organic additives [3.91], perovskite-type and superconducting layers [3.92], steel [3.93, 3.94], surface deposition [3.95], sub-surface diffusion [3.96], sensors [3.97-3.99], soil [3.100], and thermal barrier coatings [3.101]. 

Superconducting tube, 23 802 Superconducting tunnel junctions (STJs), 23 870-871 tantalum for, 23 829 Superconductivity, 23 801-881 applications of, 23 853 bulk materials applications for, 23 865-870 ceramics, 5 603-605 discovery of, 23 801 in fixed and stabilized levitation, 23 866-867... 

There are presently four families of high-temperature superconductors under investigation for practical magnet applications. Table 11-25 shows that all HTS are copper oxide ceramics even though the oxygen content may vary. However, this variation generally has little effect on the physical properties of importance to superconductivity. 

In addition to exhibiting superconductivity at temperatures, above the boiling point of liquid nitrogen (77 K), these ceramic materials can sustain very high currents, an important characteristic necessary for any large-scale application. More recent results have shown that materials containing thallium and calcium ions in place of the lanthanide ions super- J... 

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