B2223 High Temperature Superconductor Wires in Silver Sheath, Filament Diameter Effect on Critical Temperature and Current Density

Abstract

B2223 High Temperature Superconductor (HTSC) has been prepared as a pellet by solid state reaction. Then, HTSC wires were fabricated from the prepared superconductor using powder in tube (PIT) method utilizing silver as the tube material. Superconductor powder was packed in the pure silver tube of about 4.5mm diameter, and 50mm long. The prepared wires are of three types; with monofilament MOF, 9 multifilament core (9MF) and 81 filaments core(81MF). Several cycles of mechanical are drawing and rolling process performed to the starting silver tube of 0.4cm diameter and 5cm length and 0.35mm thickness to minimize the filament diameter. The average filament diameter of MoC with 0.7mm SC core which was produce by the first step of drawing, the second 9 MF wire with nine multifilament wire of 0.175mm diameter for each filament,while the 81MFC wire filament diameter was about 25μm for each filament measured with an optical microscope. All the three types of wires were with same outer diameter of 0.9mm. Tc critical temperature for superconductivity is measured for the pellet and wires using four point probes techniques. The critical temperature for the pellet is 110 °K, for the monofilament MOF is 112.5 °K and for 9 filaments 9MF was found is 117°K; while the Tc the 81MF was 119.5°K. The critical current density for the 9MF and 81MF wires were found higher than that of the monofilament MOF in spite of the smaller filament diameters of the 9 MF and 81MF. X-ray diffraction pattern shows the high Tc phase of B2223 compounds in addition to low phase, of B2212 compounds. The I-V curves for the three different wires show higher current density for 81 MF wire, while the optical microscope picture shows more grains alignment . MOC and 9 MF wires show misalignment grains.