BULK SUPERCONDUCTIVITY AT AN ELEVATED-TEMPERATURE (T(C)APPROXIMATE-TO-12-K) IN A NICKEL-CONTAINING ALLOY SYSTEM Y-NI-B-C

We report here our discovery of bulk superconductivity at rather high T(c) in samples having nominal compositions YNi4BC0.2 (T(c) almost-equal-to 12.5 K) and YNi2B3C0.2 (T(c) almost-equal-to 13.5 K). While YNi4BC0.2 seems to be a single phase material, YNi2B3C0.2 is a multiphase system. Our experimental results show that the two materials axe distinct superconductors. Discovery of superconductivity in these materials is of significance since not only is their T(c) high (> 10 K) but they also have nickel in large proportions. No nickel-based ternary superconductor was previously known.