Fabrication and transport studies on PrBa₂(Cu_1-xM_x)₃O₇: M = Ga, Zn, and Co

We have fabricated M-doped PrBa₂Cu₃O₇ (Pr123), i.e. PrBa₂(Cu_1-xM_x)₃O₇ for M = Zn, Ga, and Co, with x = 0.05, 0.10, 0.15, and 0.20. Experimental data indicates single phase samples for the Ga and Co doping up to 20% level. Second phases appear in Zn-doped samples when the doping level reaches 0.15. At 77 K the electrical resistivity of these compounds is several orders of magnitude higher than that of undoped Pr123. We also found no orthorhombic to tetragonal phase transition in the doped samples with all samples remaining in orthorhombic. Their lattices parameters are very close to those of YBa₂Cu₃O_7-δ (Y123). For this reason these compounds may serve as improved buffer-layer materials for Y123 superconducting electronic circuits and devices.