SUPERCONDUCTIVITY OF PR2-XCEXCUO4-CRYSTALS WITH SUBSTITUTION OF NI AND CO ON THE CU POSITION(DELTA SINGLE)

We report magnetic susceptibility, electrical resistivity, and Hall-co efficient measurements on single crystals from the electron-doped high -T-C superconductor Pr2-xCexCuO4+delta with Cu replaced by Ni and Co p artly. The impurities on the Cu position lead to a strong increase of the residual resistivity of about 450 mu Omega cm/at. % substitution, T-C is suppressed at a rate of -20 K/at. % substitution for both, Ni a nd Co, in quantitative agreement with previously published results on polycrystalline samples. We find that the Hall coefficient R(H) is str ongly shifted towards positive values with increasing concentration of Ni and Co, simultaneously the low-temperature upturn in R(H)(T) is su ppressed. This indicates a different impurity scattering rate for the hole and electron type of charge carriers coexisting on the Fermi surf ace of the electron doped superconductors.