The maximum sintering temperature and electrical characteristics of the high-Tcsuperconductor YBa2Cu3O7-x

Abstract

The high-T_c superconductor YBa₂Cu₃O_7-x has been found to become more 'metallic' as the maximum sintering temperature is increased from 1187 to 1234 K. The superconducting transition width also becomes narrower and smoother with a slight increase in the transition temperature. These improved electrical characteristics have been found to be associated with larger particle size and better long-range ordering of the Cu-O linear structure. On the basis of the effective-medium approximation, the authors also argue that the observed behaviour of the logarithmic temperature derivative of normal state resistivity is not controlled by densification or preferential orientation of the c axis perpendicular to the disc surface of the sintered pellets.