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Feng F.,Tsinghua University | Huang R.,Guangdong University of Technology | Qu T.,Tsinghua University | Zhu Y.,Tsinghua University | And 6 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2016

In the fabrication of YBa2Cu3O7-δ (YBCO) high-temperature superconducting films using a metal organic deposition (MOD) method, the formation of a/b-axis-orientated grains was a common detrimental factor. In this study, Pb addition was utilized to modify the MOD process, and significant improvements of YBCO film's properties were observed. Using the precursor solution prepared with or without lead acetate, YBCO films with the thickness of 600 nm were obtained for comparative study. It was found that the a/b-axis-orientated grains could be efficiently suppressed by Pb addition; thus, the critical current density was enhanced from 0.96 to 2.80 MA cm-2 (77 K, self-field) at the crystallization temperature of 780 °C. Pb was not detected in the final YBCO film. By analyzing the film samples quenched in the crystallization step of heat treatment, it was supposed that the Pb addition could help to optimize the nucleation of YBCO films and then evaporated because of its volatile behavior. © 2016 IEEE.

Bao R.,Innova Superconductor Technology Company Ltd | Song X.,Innova Superconductor Technology Company Ltd | Chen S.,Innova Superconductor Technology Company Ltd | Sun H.,Innova Superconductor Technology Company Ltd | And 3 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2013

High-temperature superconducting (HTS) (Bi,Pb)2 Sr 2Ca2Cu3O10Ag superconducting tape (Bi-2223 tape) is made mainly by three process steps including preparation of precursor powder, mechanical deformation, and heat treatment of the tape. Recently, our main efforts have been made to improve the precursor powder. With nitrates and nitric acid as main starting materials, and using spray drying and other technology, an effective process of making precursor powder for Bi-2223 tape has been developed. This paper reports this process in detail and the influences of powder processing parameters on the tape properties, such as aliquation of composition, particle size, as well as residual oxynitride, carbon, and water. By optimizing powder preparation parameters, high-quality Bi-2223 tape with critical current of about 150 A (77 K, self field) was made. © 2002-2011 IEEE.

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