Niobium diffusion in niobium-doped titanium dioxide

The present work studied the self-diffusion coefficient of (93)Nb in Nb-doped TiO(2) single crystal (4.3 at.% Nb) at high oxygen activity [p(O(2)) = 21 kPa] over the temperature range 1,073 to 1,573 K. The diffusion-induced (93)Nb concentration profile was determined by using secondary ion mass spectrometry ( SIMS). The subsequently determined self-diffusion coefficient of 93Nb exhibits the following temperature dependence: D(93Nb) - 1.77 x 10(-9) m(2) s(-1) exp(-197 +/- 9 kJ mol(-1)/RT). This study builds upon a similar study performed previously for (93)Nb tracer diffusion in undoped TiO(2), and identifies the effect of compositional change on self-diffusion behaviour. The obtained activation energy has been considered in terms of migration and formation enthalpies of titanium vacancies.