DIFFUSION-COEFFICIENTS OF OXYGEN IN ND2CUO4-DELTA

The chemical diffusion in Nd2CuO4-δ was measured by means of a thermomicrobalance in a temperature range of 650 to 900°C under oxygen pressure of 1 to 0.01 atm, using dense polycrystalline specimens. It was found that the relaxation after a step change in oxygen pressure from 0.3 to 0.01 atm was exponential, and the reduction rate coincided with that of oxidation. From this result, the relaxation was concluded to obey diffusion-controlled kinetics, and the chemical diffusion coefficient was determined. The self-diffusion coefficient of oxygen and the oxygen vacancy diffusion coefficient were calculated from the chemical diffusion coefficient. The self-diffusion coefficient of oxygen in Nd2CuO4-δ was slightly larger than that in perovskites, and lower than that of YBa2Cu3O6.4. The vacancy diffusion coefficient of Nd2CuO4-δ is almost the same as that of perovskite-type oxides. © 1991 Academic Press, Inc.