Processing of Bi2Sr2CaCu2Ox thick films from nitrate precursors

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.

Nanostructured high-temperature superconductors: Creation of strong-pinning columnar defects in nanorod/superconductor composites

“…32 The BSCCO films were deposited in 50 -200 mTorr of oxygen with substrate temperatures of 25 and 650 ± C. Next, the thick films produced in this way were partially melted in a tube furnace at 880 ± C for 15 min, and then slowly cooled to form textured superconducting thick films. 33 Films prepared by deposition at both temperatures exhibited similar texture, although microcracks were reduced in samples deposited at 650 ± C. 34 Nanorod/BSCCO-2223 composite films were prepared by laser deposition of Bi 1.8 Pb 0.3 Sr 2 Ca 2 Cu 3 O z targets at 680 ± C followed by annealing at 800-810 ± C in air. 35 The as-prepared BSCCO-2212 and 2223 samples were then post-annealed in flowing Ar at 350 ± C for 3 h to optimize the superconducting transition temperature, T c .…”

“…In general, high-quality nanorod/BSCCO-2212 composites and reference BSCCO-2212 samples have been made through the use of standard melt-texturing procedures 20,33 that produce polycrystalline samples with well-oriented (textured) grains. X-ray diffraction studies of the composites show that the partial meltingcooling cycle leads to crystalline, textured BSCCO-2212 [ Fig.…”

Stability of supercurrents in a BiSrCaCuO (Bi-2212) high- Tcsuperconductor with artificially created defects

“…The original tapes were prepared at SUNY, Buffalo by Li et al [1]. Proton irradiations were performed at the Los Alamos Meson Physics Facility (LAMPF) by P. Lisowski and J. Ullmann, and subsequent transmission electron microscopy (TEM) studies of the fission-generated tracks were performed by R. Wheeler of the Argonne National Laboratory (now at Ohio State University).…”

Al2O3 additions for isothermal melt processing of Bi2Sr2CaCu2Oy

“…[1][2][3][4] However, controlling the phase assemblage during and after partial melting can be difficult due to the incongruent melting of Bi-2212. [1][2][3][4] However, controlling the phase assemblage during and after partial melting can be difficult due to the incongruent melting of Bi-2212.…”

“…7 A similar problem arises during isothermal melt processing where the partial melt is formed by melting in an inert atmosphere. [1][2][3][4][8][9][10][11] In this paper, the approach taken is to use an additive with the nominal Bi-2212 stoichiometry that inhibits the growth of phases in the partial melt. In a recent study, for example, large alkaline-earth cuprates, alkaline-earth bismuthates, and the low-temperature superconductor, Bi 2 Sr 22x Ca x CuO y (Bi-2201), were found in thick films isothermally melt processed above 800 ± C. 12 In either approach to the melt processing of Bi-2212, the underlying problem is the uncontrolled growth of solid phases present in the partial melt.…”