SUPERCONDUCTIVITY AT 23-K IN YTTRIUM PALLADIUM BORIDE CARBIDE

COPPER oxide compounds have dominated superconductivity research since 1986 because of their very high transition temperatures (T(c)s). In contrast, no new families of high-T(c) intermetallic compounds have been discovered since the A15-type Nb3X compounds were first reported in 19531. The intermetallics with highest T(c)s have all been based on niobium, with the highest T(c)s being 20.7 K for bulk Nb3Ga and 23.2 K for sputtered films of Nb3Ge (refs 2, 3). Here we report the observation of superconductivity at 23 K in a multiple-phase bulk sample of a quaternary intermetallic, yttrium palladium boride carbide. This is higher than any T(c) reported previously for a bulk intermetallic compound. Although the materials are not yet single-phase, the superconducting volume fraction is large. We propose that this compound may represent the first of a new family of superconducting intermetallics with relatively high T(c)s.