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

We report measurements of the resistivity (rho(T)), Hall coefficient ( R(H)), thermoelectric power (S) and AC susceptibility of a polycrystal line sample of Co-doped YBa2Cu3O7 in which the grain-boundary resistan ce could be drastically altered without affecting the properties of th e individual grains. Our results show that although the shape and magn itude of rho(T) are strongly changed by the increase in grain-boundary scattering, there is no corresponding effect in either the thermoelec tric power or the Hall coefficient. These results suggest that measure ments of the temperature dependence of R(H) and S made on stoichiometr ic polycrystalline samples should accurately reflect those of the grai ns.