Niobium diffusion in niobium-doped titanium dioxide

The present work studied the self-diffusion coefficient of 93Nb 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 93Nb concentration profile was determined by using secondary ion mass spectrometry (SIMS). The subsequently determined self-diffusion coefficient of 93Nb exhibits the following temperature dependence: 93Nb= 1.77 x10 -9m 2s -1 exp (- 197 +9kJml -1/RT. This study builds upon a similar study performed previouslyfor 93Nb 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