Platinum Metals Rev., 1994, 38, (2), 56
High Temperature Palladium Superconductor
Since the first high temperature YBaCuO superconductors were found in 1986, there has been much research to establish their basic mechanism and to find modifying elements which would increase the critical temperature. Copper oxides have usually been employed in these superconductors since they have a very high transition temperature, but no new families of inter metallic compounds with high transition temperatures have been discovered since the niobium binaries in 1953.
Now however, researchers at AT&T Bell Laboratories in New Jersey, the University of Tokyo and the Technical University, Delft, have reported superconductivity at 23 K in a multiple-phase bulk sample of yttrium palladium boride carbide. (R. J. Cava, H. Takagi, B. Batlogg, H. W. Zandbergen, J. J. Krajewski, W. F. Peck, R. B. van Dover, R. J. Felder, T. Siegrist, K. Mizuhashi, J. O. Lee, H. Eisaki, S. A. Carter and S. Uchida Nature, 1994, 367, (6459), 146–148).
The transition temperature of this palladium quaternary intermetallic is higher than that of any previously reported for a bulk intermetallic compound. The superconductivity was observed for a narrow range of compositions at relatively low carbon contents. The superconducting volume fraction was large, even though the material was not single-phase. In addition, superconductivity was observed in small quantities in yttrium-palladium-boron alloys with no added carbon. It is suggested that yttrium palladium-boride carbide may be a new family of high-transition temperature superconductors.