TRANSPORT AND ELECTRONIC-PROPERTIES OF Y0.4PR0.6BA2-YCU3O7-DELTA (Y =0, 1.0)

We report measurements of the resistivity, thermoelectric power and Ha ll carrier number on Y0.4Pr0.6Ba2-ySryCu3O7-delta (y = 0, 1.0) polycry stalline samples. The Sr-free compound exhibits semiconducting behavio r, while the Sr-doped sample is superconducting at 18 K with a possibl e pseudogap structure at 255 K. Results of the thermoelectric power an d Hall measurements revealed that the revival of superconductivity by the Sr substitution is due to the increase of mobile hole-concentratio n. We present a band picture of Pr4f-O2p hybridization to elucidate th e variation of the transport properties.