Spectroscopic investigations of adsorption during fabrication of Ag/(Bi, Pb)₂Sr₂Ca₂Cu₃O_x superconducting tape

Intrusion and inheritance of adsorbed gases during fabrication of silver-sheathed (Bi, Pb)₂Sr₂Ca₂Cu₃O_x (2223) superconducting tape (Ag/Bi-2223) are confirmed and studied by Fourier transform infrared spectroscopy, x-ray photoemission spectroscopy and Auger electron spectroscopy. Handling in air of precursor powder (BPSCCO powder), composed of (Bi, Pb)₂Sr₂CaCu₂O_x (2212), (Ca, Sr)₂PbO₄, (Ca, Sr)₂CuO₃, CuO and (Bi, Pb)₂Sr₂CuO_x (2201), causes the physisorption of CH₂ or CH₃, O₂, CO₂, H₂O and carbide and chemisorption of CO₂ and H₂O to form CO₃ groups and hydroxyl on the powder. These adsorbates are inherited by the superconducting layer of the Ag/Bi-2223 tape and exist at grain boundaries of the 2223 phase to form weak links, which dramatically degrade the intergrain critical current density (J_c). Mechanisms of intrusion and inheritance of adsorbates are systematically discussed. Our results highlight the importance of atmosphere control during the handling of BPSCCO powder for obtaining high-J_c tape.