The resistive transition in high magnetic fields in YBa2(Cu1-xZnx)3O7-δ

We have investigated the resistive transition in a series of Zn substituted ceramic YBCO samples, both in zero field, and in fields up to 17.5 T. We studied samples with Zn concentrations x of up to 10%. The lowest Tc was observed for x=9%, where Tc (R=0) is at 700 mK. The normal state resistance shows a linear temperature dependence down to the superconducting onset. For the x=9% Zn sample, this linear region extends to 1.8 K. In magnetic fields the resistive transition broadens considerably, and the R=0 transition moves to below 100 mK. The resistive transitions can be understood in terms of thermally activated flux creep. (orig.)