Processing of Bi2Sr2CaCu2Ox thick films from nitrate precursors

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Abstract
High‐quality Bi2Sr2CaCu2Ox/Ag superconducting tapes were fabricated directly from the nitrate salts of Bi, Sr, Ca, and Cu by the partial‐melt‐growth technique. Nitrate particles were deposited electrostatically on the Ag substrate and heat treated. After process optimization of the superconducting tapes, the best samples showed typical Tc of 89 K with zero applied field critical current density of 2×104 A/cm2 (Ic=11.2 A) at 77 K and 2.6×105 A/cm2 (Ic=190 A) at 4.2 K. Unlike films grown using solid state reacted precursor powders, these films lacked the typical Bi‐free, needlelike defects and possessed a smooth morphology. X‐ray diffraction patterns showed the film to be highly c‐axis oriented. The processing of these tapes significantly reduces the overall fabrication time from precursor materials preparation to final heat treatment.