Structure and transport studies on PrBa2(Cu1-xMx)3O7:: M=Al, Fe, and Ni

We have fabricated metal doped PrBa2Cu3O7 (PBCO), i.e. PrBa2(Cu1-xMx)(3)O-7 (PBCMO) with M = Al, Fe, and Ni, and x = 0.05, 0.10, 0.15, and 0.20, X-ray data indicate no significant second phase for Ni-doped samples until 15% doping level is reached. No second phase was found in Al- and Fe-doped samples up to the 20% doping level. All the doped samples are in orthorhombic structure and their lattice parameters are very close to those of YBa2Cu3O7-delta (YBCO). However, for Al or Fe doped samples the difference in lattice parameters a-b has decreased from that of PBCO. At 77 K the electrical resistivity for Al- or Fe-doped samples is several orders in magnitude higher than that of PBCO. Therefore these compounds may be better buffer-layer materials for YBCO superconducting electronic circuits and devices.