Browsing by Subject "BSCCO"
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Item Bi-Sr-Ca-Cu-O thin films grown by flash evaporation and pulsed laser deposition(Texas A&M University, 2004-09-30) Ganapathy Subramanian, SanthanaBismuth-Strontium-Calcium-Copper-Oxide (BSCCO) compounds are an important family of compounds that have one of the highest transition temperatures among all high-temperature superconductors. The compound is known to exist in three distinct phases, commonly referred to as the 2201, 2212 and 2223 phases. Of these three phases, the 2212 and 2223 phases are the most important, as their transition temperature is higher than the boiling point of liquid nitrogen. It is desirable to produce the compound in thin film form, as the bulk samples are normally polycrystalline. This thesis compares thin films produced by two techniques for depositing BSCCO in order to understand the effect of various processing parameters on the final quality of the thin films. Thin films were grown by flash evaporation at Texas A&M University, and by pulsed laser deposition (PLD) at the University of Wollongong, Australia. The latter of these techniques is widely used for growing thin films of various compounds. Single-phase 2212 films were grown on a MgO substrate using the pulsed laser deposition technique from commercially available 2212 powder. The effect of annealing on the thin films was also studied.Item Optimization studies on thermal and mechanical manufacturing processes for multifilament superconducting tape and wire(Texas A&M University, 2004-11-15) Basaran, BurakThere are many parameters that significantly affect the electrical performance of ceramic-core superconducting composite wire and tapes, which remain ambiguous and require more labor on their optimization. BSCCO 2212 has not been paid the attention and investment it deserves. In this regard, all optimization efforts were made for BSCCO 2223. In our work, a practical and inexpensive manufacturing method, thermally and mechanically optimized for Pb doped BiSrCaCuO 2212 superconducting multifilament (38 filaments) wires and tapes, was successfully employed. Optimized parameters can be classified under material, mechanical (deformation) and heat treatment (thermal) subgroups. Parameters involved with materials included investigation of deformation behavior of two different sheath metals; pure silver and 0.02% magnesia dispersion reinforced silver alloy. Pb doped BiSrCaCuO 2212 ceramic superconductor powder, the other source of material related parameters, was synthesized following the "Thermal Co-decomposition or Wet Mix" method. Fabrication of mono and multifilament wires with Oxide Powder in Tube (OPIT) method followed next. Optimization of drawing deformation was practiced to achieve the best ceramic grain alignment and smoother ceramic powder core/metal sheath interface in order to avoid "sausaging" in wires. Rolling of the wire products into tapes by following different deformation regimes was the other manufacturing stage of the project. Variable and constant reduction-per-pass deformation paths were employed to reveal their effects on our composites with distinct sheath material and filament formation. The search for the best (optimum) heat treatment schedule for our Bi2212 superconductor composites, a modified version of "step solidification partial melting", was employed successfully. A solution through tried recipes for the bubbling problem that occurred with our tapes was also addressed. Electrical performance tests of fully reacted wires were carried out in our laboratory and very promising results were attained.