CONCENTRATION-DEPENDENCE OF OXYGEN DIFFUSIVITY IN GDBA2CU3O6+Y FILMS

Oxygen diffusion in the perovskite-related nonstoichiometric oxide GdB a2Cu3O6+y has been investigated in situ on thin films using high-tempe rature resistive measurements. Except for a step change in the vicinit y of the orthorhombic-tetragonal structural transition, the diffusivit y shows no concentration dependence over a wide interval (0.3 < y < 0. 8). The activation energy is constant in the whole measured interval ( E-o approximate to 1.2 eV). It is proposed that oxygen diffusion propa gates via vacancy mechanism, involving the oxygen atoms at the extreme s of the -O-Cu-O-chains in the basal plane.