INFLUENCE OF GRAIN-BOUNDARY SCATTERING ON THE TRANSPORT-PROPERTIES OF A HIGH-TC OXIDE SUPERCONDUCTOR

We report measurements of the resistivity (rho(T)), Hall coefficient (R(H)), thermoelectric power (S) and AC susceptibility of a polycrystalline sample of Co-doped YBa2Cu3O7 in which the grain-boundary resistance could be drastically altered without affecting the properties of the individual grains. Our results show that although the shape and magnitude of rho(T) are strongly changed by the increase in grain-boundary scattering, there is no corresponding effect in either the thermoelectric power or the Hall coefficient. These results suggest that measurements of the temperature dependence of R(H) and S made on stoichiometric polycrystalline samples should accurately reflect those of the grains.