SUPERCONDUCTIVITY OF 22-K AND 10K IN THE QUATERNARY BOROCARBIDES RPD4BCX (R=Y, LU)

Recently we reported superconductivity in Y-Ni-B-C system, the first known quaternary superconducting system. One of the superconducting materials reported by us had the nominal chemical composition YNi4BC0.2. We examine, in this paper, effect of replacing nickel by palladium which is an obvious and natural step for us since we believe that the d-electrons are carriers of superconductivity in these materials. Our samples with the nominal composition YPd4BC(x) (0.2 < x < 1) have a superconducting minority phase with transition onset temperature as high as 22 K. Some of the samples show another superconducting transition at approximately 10 K, indicating one more superconducting phase in this sytem. We have also investigated LuPd4BC0.2, (Lu being the end member of the rare earth series) which also shows existence of a superconducting phase with T(c) approximately 10 K.