Neutron irradiation and post-irradiation annealing of rutile (TiO2-x):: effect on hydrogen incorporation and optical absorption

Neutron irradiation and post-irradiation annealing under oxidising and reducing conditions have been used to investigate H incorporation in, and the optical properties of, reduced (TiO2-x ) rutile. Optical absorption in rutile is mainly due to a Ti3+ Ti4+ intervalence charge transfer effect. The main mechanism for H incorporation in rutile involves interstitial H not coupled to other defects, which has important implications for the rate of H diffusion, and possibly also on the electrical properties of rutile. Additional minor OH absorption bands in IR spectra indicate that a small amount of interstitial H is coupled to defects such as Ti3+ on the main octahedral site, and indicates that more than one H incorporation mechanism may operate. Concentration of oxygen vacancies has a controlling influence on the H affinity of rutile.