Diffusion of Oxygen in Near-Stoichiometric α-Nb2O5

Oxygen diffusion coefficients have been determined for near-stoichiometric α-Nb2O5 over the temperature range of 850° to 1200°C and the oxygen pressure range of 10−2 to 1 atm. At a constant temperature, the diffusion coefficient is found to be proportional to pO2−1/4. Temperature dependence of the diffusion coefficient at a constant oxygen pressure is expressed (in square centimeters per second) by D=1.72×10−2× exp[— (49.4±3.3 kcal) / RT]. Results are discussed in terms of an oxygen-vacancy model of nonstoichiometric disorder.