Ba2YCu3O7-δ tapes were fabricated by cold rolling. The critical current density Jc apparently depended on the thickness of the tape and increased markedly with decreasing tape thickness. The maximum Jc of 3330 A/cm2 at 77 K in a zero magnetic field was achieved in an Ag-sheathed BYCO tape, 0.06 mm in thickness. The presence of a 20 mT magnetic field reduced the Jc value by 1/100.

Fabrication of Ag-Sheathed Ba-Y-Cu Oxide Superconductor Tape : Electrical Properties of Condensed Matter

Ba2YCu3O7 superconducting tape was successfully fabricated by the so-called doctor blade casting process. A zero-resistance state was achieved at 91.5 K for the tape heat-treated at 1000°C. The highest Jc was about 110 A/cm2 at 77 K and in zero magnetic field. The green sheet in an as-cast state has sufficient flexibility to be wound into a small diameter, making possible the winding and the sintering processes in future applications for superconducting coil.

Superconducting Properties of Ba-Y-Cu-O Tape Prepared by the Doctor Blade Process : Electrical Properties of Condensed Matter

Abstract In-plane aligned superconducting Tl 0.78 Bi 0.22 Sr 1.6 Ba 0.4 Ca 2 Cu 3 O 9 ((Tl,Bi)-1223) films on R olling A ssisted Bi axially T extured S ubstrates (RABiTS) with J c of 4.25×10 5 A/cm 2 at 77 K and zero-field have been synthesized by laser ablation and post-ablation annealing. The as-ablated films were amorphous due to the low substrate temperature during ablation. The amorphous films were then wrapped together with an unfired Tl 0.95 Bi 0.22 Sr 1.6 Ba 0.4 Ca 2 Cu 3 O 9 pellet in silver foil. The whole package was finally annealed in a tube furnace at 780–810°C for 40–60 min in flowing argon to crystallize the films. X-ray diffraction (XRD) shows that the annealed films consist of mainly c -axis aligned (Tl,Bi)-1223 phase with a small amount of (Tl,Bi)-1212 phase. The full width at half maximum (FWHM) values of XRD peaks show that both phases are epitaxial, with in-plane and out-of-plane alignments comparable to those of the underlying Ni and buffer layers (CeO 2 and YSZ). Four-probe transport measurements showed superconducting transition temperatures ( T c s) of 105–109 K depending on the annealing conditions. With external magnetic field applied parallel to the c -axis, irreversibility magnetic fields reached beyond 3 T at 77 K and beyond 5 T at 64 K.

保坂純男

Papers

レーザー成膜法による銀基板上へのTl-1223 膜形成と Jc の温度依存性

保坂 純男

Papers

レーザー成膜法による銀基板上へのTl-1223 膜形成と Jc の温度依存性

保坂純男