SCATTERING PHASE-SHIFTS IN NI AND ZN DOPED Y-123

Cu-site substituted thin films of YBa2(Cu(1-z)M(z))(3)O-7-delta (M=Zn, Ni) are reinvestigated. The T-c-suppression and residual resistivities rho(0) are measured as a function of the concentration z. We found th at for low concentrations z less than or equal to 4% the substituents occupy preferrably the in-plane Cu sites whereas for higher concentrat ions the chain sites are also occupied. Although the residual resistiv ities of Ni and Zn differ only slightly, the T-c-suppression of Zn is 2.3 times larger than that of Ni. To reconcile the measured resistivit ies with predictions of a two dimensional scattering model, it is nece ssary to assume a scattering potential of finite range and to tate sca ttering phase shifts delta(l) of higher angular momentum (1 > 0) into account. The different T-c-suppression rates for Zn and Ni are also di scussed within this picture.