PrBa2[Cu1-xMx]3O7 AS I-LAYER MATERIALS FOR JOSEPHSON SIS JUNCTIONS

Abstract

Metal (M) doped PrBa 2 Cu 3 O 7, i.e. PrBa 2( Cu 1-x M x)3 O 7 for M = Al , Co , Fe , Ga , Ni and Zn , and x =0.05, 0.10, 0.15, and 0.20 were fabricated. No significant second phase was found for the Al , Co , Fe and Ga doped samples up to 20% doping level. Impurity phases, however, were detected for Ni and Zn doped samples when doping concentration reached 15% and higher. At 77 K the electrical resistivity for most of these compounds is several orders in magnitude higher than that of the PrBa 2 Cu 3 O 7-δ. Although the lattice parameters in the doped samples changes toward tetragonal structure, all sample remained in orthorhombic structure and the parameters remain very close to those of the undoped one and YBa 2 Cu 3 O 7-δ. For this reason these compounds may serve as improved I-layer materials for making YBa 2 Cu 3 O 7-δ SIS Josephson junction.