ISSN:
1572-9605
Keywords:
Tl-superconductors
;
preparation
;
critical currents
;
texturing
Source:
Springer Online Journal Archives 1860-2000
Topics:
Electrical Engineering, Measurement and Control Technology
,
Physics
Notes:
Abstract Doped Tl-1223 superconductors of the composition TlaBibPbcBanSr2−nCa2Cu3Oy (a = 0.50 − 0.76, b = 0, 0.16 and 0.3, c = 0.5, 0.24 and 0, n = 0.15 − 0.4) were prepared from oxidic Ba-Sr-Ca-Cu precursor material. Upon calcination of the tartrate gels or the nitrates, the respective amounts of Tl2O3, PbO and Bi2O3 were added to the oxidic powders by milling. The samples were sintered in silver foil. The specimens consisted predominantely of the Tl-1223 phase with small amounts of Tl-1212 and secondary phases. Tc(0)-values ranged between 115 K and 119 K with transition widths around 1 K. Transport critical current densities up to 1.4 kA cm−2 at 77 K were measured for the assintered samples. Texturing was obtained by repressing and resintering of the superconducting material followed by annealing at 750°C for 50 h in flowing oxygen. The transport critical current densities could be improved up to 7 kA cm−2 by the thermomechanical treatment. Microstructural studies yielded information on the alignment of the superconducting grains, on secondary phases and the porosities.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1022662703194
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