ESR investigation of Fe3+ diffusion in rutile

The electron spin resonance (ESR) technique was used to investigate the diffusion of Fe3+ in rutile (TiO2). ESR absorption intensity was measured for several annealing times and three different temperatures of isothermal annealing: 1273, 1323 and 1373 K. The activation energy for diffusion, calculated from the experimental data using a theoretical model based on the Fick equation, was found to be E(A) = 215 kJ mol(-1). This result is consistent with experimental data using the radioactive-tracer sectioning technique and represents an independent measurement of the activation energy for diffusion of trivalent iron in rutile, which is difficult to achieve by other means in this mixed-valence system.