Effect of composition on critical current density of Bi2212/Ag round wires Original Research Article

We have fabricated Bi2212/Ag round wires using three kinds of precursor to study the effect of a narrow variation of composition. Slightly different compositions – Bi2.17Sr1.94Ca0.89Cu2.0Ox(N13), Bi2.15Sr1.94Ca0.89Cu2.0Ox(N14), and Bi2.17Sr1.98Ca0.89Cu2.0Ox(N15) – were used and Sr/Ca ratio of them were 2.18, 2.18, and 2.22, respectively. The Ag ratios of the wires were 2.7–2.8 and average filament diameter was 19–21 μm. DTA analysis of the wire showed the peritectic temperature of three wires was very similar value of the range of 880–881 °C. The best engineering critical current density (Je) of three wires at 4.2 K and 0 T was 414–448 A/mm2 at the maximum process temperature range of 884–892 °C. The n-value of N14 showed 13.6, whereas other two wires showed lower n-value, estimating the existence of micro-cracks. Although Bi2212/Ag round wires fabricated by three kinds of composition showed similar Je value, n-value was quite different. It is likely that the fabrication process such as the drawing as well as the composition of precursor will affect on Je of Bi2212/Ag round wire.