Low-melting liquids in high-temperature superconductor precursor systems. (News Briefs).NIST (National Institute of Standards & Technology, Washington, DC, www.nist.gov) The standards-defining agency of the U.S. government, formerly the National Bureau of Standards. It is one of three agencies that fall under the Technology Administration (www.technology. researchers are characterizing the phase equilibria of liquids in the Ba[F.sub.2]-BaO-[Y.sub.2][O.sub.3]-[CuO.sub.x]-[H.sub.2]O system, in order to provide data essential for the reproducible processing of low-cost, second generation, high-temperature superconductor A material that has little resistance to the flow of electricity. Traditional superconductors operate at absolute zero (-459.67 degrees Fahrenheit or -273.15 degrees Celsius). Experiments in the 1980s raised the temperature to -321 degrees Fahrenheit. wire and cable. As concern increases about the supply of non-renewable energy resources and global environmental issues, high temperature superconducting su·per·con·duct·ing adj. Having, exhibiting, or capable of superconductivity: "a revolutionary superconducting magnetic propulsion system" Colin Nickerson. materials remain attractive as part of potential solutions for improving the efficiency of energy distribution and utilization. Key is the availability of low-cost, long-length, high-performance wire and cable. Commercial scale-up is beginning for fabrication fabrication (fab´rikā´sh  n),n the construction or making of a restoration. of long-length cable using first generation materials based on Bi-Sr-Ca-Cu oxide (BSCCO BSCCO Bismuth Strontium Calcium Copper Oxide BSCCO Balancing and Settlement Code Company (UK) ) high-temperature superconductors. However, this is still a relatively high-cost process, which may limit large-scale application in the utility industry. Consequently, NIST researchers, sponsored by the Department of Energy (DOE), are investigating second generation high-temperature superconducting materials based on Y-Ba-Cu oxide (YBCO YBCO Yttrium Barium Copper Oxide YBCO Yttrium Barium Cuprate ) coated metallic conductors. These materials can be processed in tape form using thin-film deposition methods, potentially reducing the costs associated with the rather complex powder-in-silver tube process used for BSCCO. One of the most promising YBCO coated conductor processing routes is the fabrication of B a[F.sub.2]-containing precursor films which are then converted to oxide superconductor through reaction with water-vapor. A relatively low temperature (<730 [degrees]C) liquid is thought to be involved, the control of which can greatly influence the kinetics kinetics: see dynamics. Kinetics (classical mechanics) That part of classical mechanics which deals with the relation between the motions of material bodies and the forces acting upon them. of conversion and the resulting texture and transport properties of the superconductor. By studying the [BaF.sub.2]-YBCO precursor system under carbonate-free conditions using specially constructed apparatus, NIST researchers have identified regions in multidimensional phase space where liquids occur at temperatures lower than 700 [degrees]C. CONTACT: Larry Cook, (301) 975-6114; lawrence.cook@nist.gov or Winnie Wong-Ng, (301) 975-5791; winnie.wong-ng@nist.gov. |
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