Oxygen diffusion into oxygen-deficient Ba2YCu3O7-x films during plasma oxidation

We studied the speed of oxygen diffusion into deoxygenated Ba2 YCu3 O7−x films during plasma oxidation. The films were deoxygenated by annealing in N2 or Ar and treated in an oxygen plasma. The sample was below 160 °C during the plasma oxidation. The deoxygenated film was tetragonal and exhibited semiconductivity. Plasma oxidation changed the crystal structure of the film from tetragonal to orthorhombic, and restored superconductivity and metallic behavior in the oxygen deficient film. The change in composition variable x calculated from the weight gain during plasma oxidation was about 0.6. The effective diffusion constant for oxygen indiffusion estimated from the time dependence of weight gain was on the order of 10−12 cm2 /s.