Neutron irradiation and post-irradiation annealing of rutile (TiO2−x ): effect on hydrogen incorporation and optical absorption
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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.
KeywordsHydrogen Rutile Spectroscopy Neutron irradiation Radiation defects
This work was funded by the Bayersiches Geoinstitut visiting scientists program (to GDB) and by Alexander von Humboldt foundation (to AAS). The authors thank Dr. N. N. Dogadkin (Vernadsky Institute of Geochemistry) for performing neutron irradiation experiments. Hans Keppler is thanked for useful comments regarding H2 measurements. Comments by two anonymous reviewers greatly improved the quality of this paper.
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