Resistivity and Carrier Mobility of the SmBa2Cu306+x Superconductor with Different Oxygen Doping Levels

DC conductivity measurements between 15 and 300 K are reported for SmBa2Cu306+J samples with different oxygen doping amounts (x) produced by annealing under appropriate high temperature and oxygen pressure conditions and quenching. Samples with jc>0.5 are superconductors: 7*c~60 K at Jt=0.7, 7*c>80 K at ;c=0.9. The transition from superconduction to non-superconduction corresponds to the tetragonal to orthorhombic structural transition and to the transition from semiconducting to metallic temperature dependence of the resistivity. Oxygen doping causes a sudden increase of hole mobility near x=0.5. Below this threshold, the behavior of the carrier mobility is in agreement with an Anderson localization.