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 c ontrast, no new families of high-T(c) intermetallic compounds have bee n discovered since the A15-type Nb3X compounds were first reported in 19531. The intermetallics with highest T(c)s have all been based on ni obium, with the highest T(c)s being 20.7 K for bulk Nb3Ga and 23.2 K f or sputtered films of Nb3Ge (refs 2, 3). Here we report the observatio n of superconductivity at 23 K in a multiple-phase bulk sample of a qu aternary intermetallic, yttrium palladium boride carbide. This is high er 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 rela tively high T(c)s.