Superconductivity in YBa2Cu3-yMyO7-xsystems where M=Zn, Ni and Co

Abstract
The electrical resistance of the alloyed compounds YBa2Cu3-yMyO7-x, where M=Zn, Ni and Co, has been studied for two series of Zn-substituted (ycR=0) above 20 K except for the Zn system with y=0.30 for which TcR=0)c2/dT, has been determined.