Low-temperature oxygen diffusion in alpha titanium characterized by Auger sputter profiling

Anodic TiO2 films were grown on titanium foils under galvanostatic conditions at 20 mA/cm2 in an aqueous saturated solution of ammonium tetraborate. The samples were then heat treated at temperatures between 450 and 550 °C and changes in the profile of oxygen concentration as a function of depth were monitored using Auger electron spectroscopy (AES). The oxygen diffusivities were calculated from the Boltzmann–Matano method and compared with those obtained using an analytical solution to Fick’s second law. The activation energy for oxygen diffusion in this temperature range was then calculated to be 28 kcal/mol.