Properties of Bi₂Sr₂CaCu₂O₈ thick films melt-processed at temperatures up to 950 °C

Abstract

Thick Bi 2 Sr 2 CaCu2O 8 films have been produced by melting Bi 2 Sr 2 CaCu2O 8 powder on MgO substrates at temperatures just above the melting temperature of the powder. X-ray diffraction measurements indicate enhanced c-axis alignment throughout the thickness of the films. Films melted at 900 °C show greater alignment and contain less Bi 2 Sr 2 Cu06 compared to those processed at 950 °C. Both the degree of alignment and the Bi 2 Sr 2 Cu0 6 content increase as the cooling rate is decreased. Transport measurements show that films quickly cooled from low melt-processing temperatures have the highest critical current densities (J c -13 kA/cm 2 at 30 K). The temperature dependence of J c is best described by a flux creep model. Finally, J c at 4.2 K (in both parallel and perpendicular magnetic fields) undergoes a sudden drop at low fields, but levels off above 0.5 T to about 30% of the zero field value.

Applicability of the vortex-glass model for the single crystal Tl 0.4 K 0.41 Fe 1.71 Se 2

“…Similar curves have been seen in the case of Bi 2 Sr 2 CaCu 2 O 8 ; [12] the broadening in the low-temperature region was well explained by the flux creep behavior, within the framework of the Anderson-Kim flux creep model. Zeldov et al relates the broadening to the existence of a logarithmically shaped flux line potential well, [13] as he did to YBa 2 Cu 3 O 7 films.…”

Superconducting YBCO (Tc(0) $equal$ 92 K) and Bi-2223 (Tc(0) $equal$ 110 K) thick films on polycrystalline Ba2LaHfO5.5: a new perovskite ceramic substrate

“…However, MgO forms an interlayer of barium salt at the YBCO-MgO interface if the processing temperature is above 700 • C and reduces the superconducting transition temperature of the YBCO film considerably [9,10]. The Bi(Pb)-Sr-Ca-Cu-O films developed on MgO substrate always contained both the low T c Bi-2212 and high T c Bi-2223 phases [11,12].…”

Sample - substrate interactions during melting of Bi-2212 on Ag

“…It is a useful sheath and substrate material, which allows the preparation of macroscopic polycrystalline Bi-cuprate superconductors with critical current densities j c exceeding 3 × 10 4 A cm −2 at 77 K, 0 T [1]. If processed on substrate materials other than silver, the superconducting properties worsen or are lost completely [2,3]. Silver has been shown to influence the superconducting material in various ways.…”