Fabrication of Bi-2212/SrSO4 Composite Superconductors by Melting Powder Mixtures
We fabricated Bi-2212/SrSO4 composite superconductors by the melt casting process and evaluated the effects of the powder mixing method and melting temperature on their microstructure and superconducting properties. In the melt casting process, the Bi-2212 powders were mixed with SrSO4 by hand-mixing (HM) and planetary ball milling (PBM) and then the powder mixtures were melted at 1100°C~1200°C, solidified, and annealed. We found that the powder mixture prepared by PBM was finer and more homogeneously mixed than that prepared by HM, resulting in more homogeneous microstructure and smaller SrSO4 and second phases after annealing. The critical current (Ic) also varied significantly with the powder mixing method and the melting temperature. The Ic of the annealed rod prepared by PBM was 193 A at 77 K when melted at 1100°C, which is higher than that of the annealed rod prepared by HM (132 A). This enhancement in the Ic value for the former is considered to be due to its more uniform microstructure.
Duk Yong Yoon, Suk-Joong L. Kang, Kwang Yong Eun and Yong-Seog Kim
K. T. Kim et al., "Fabrication of Bi-2212/SrSO4 Composite Superconductors by Melting Powder Mixtures", Materials Science Forum, Vols. 534-536, pp. 1597-1600, 2007