The diffusivity under a gas pressure of 100MPa was deduced by simulating a sintering model which involved surface and volume diffusion. The value of the bulk diffusion coefficient, as estimated by using the present simulation, was similar to the O diffusion coefficient in the oxide. The present work showed that the surface diffusivity (2.2 x 10-16m2/s at 850C) under high-pressure Ar gas was about 30 times higher than that under 1atm.

Surface Self-Diffusivity of TiO2 under High-Pressure Gas. Nanko, M., Ishizaki, K.: Physical Review B, 1997, 56[11], 6965-9