AC SUSCEPTIBILITY WEAK-LINK CHARACTERIZATION IN THE BI-PB-CA-SR-CU-O THICK-FILMS ON (IN) AG TAPE

KAZIN, P.; OSKINA, T.; TRETYAKOV, Y.

Авторы: KAZIN PE, OSKINA TE, TRETYAKOV YD
Журнал: APPLIED SUPERCONDUCTIVITY
Том: 1
Номер: 7-9
Год издания: 1993
Первая страница: 1007
Последняя страница: 1013
DOI: 10.1016/0964-1807(93)90406-R
Аннотация: The thick films of the Bi-Pb-Ca-Sr-Cu-O superconductor with thickness 20 mum on (in) Ag tape have been prepared by cold rolling, pressing and annealing at 820-830-degrees-C cycles with overal thermal treatment time of 90 h. AC susceptibility data show that intragrain T(c) is about 108 K, while transport supercurrents start to flow at lower temperatures (70-102 K). The temperature dependences of the intergrain critical current density J(c)(T) have been calculated on the base of the chi''(T) data using the model worked out. On the J(c)(T) curves sometimes one can see a bend near 65 K, which may be explained by the existence of the second superconducting phase (2122), switching on new percolation paths for the supercurrents below that temperature. It has been found that low temperature distortion of chi''(T) and J(c)(T) curves is connected with cracks in the superconducting layer, the cracks restricting critical current flow through the film. The best films obtained have J(c)(77 K) 830 and 440 A/cm2 for the films in and on Ag tape accordingly. Additional annealing of these samples at 830-degrees-C for 50 h leads to the J(c) rising for the ''on Ag'' film up to 1200 A/cm2, but J(c) for the ''in Ag'' film remains the same. The J(c) rise for ''on Ag'' film is in accordance with decreasing of J(c) suppression by cracks due to sintering, while for the ''in Ag'' film this process is accompanied with partial destruction of 2223 phase.
Добавил в систему: Казин Павел Евгеньевич

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AC SUSCEPTIBILITY WEAK-LINK CHARACTERIZATION IN THE BI-PB-CA-SR-CU-O THICK-FILMS ON (IN) AG TAPEстатья