On the use of ion scattering to examine the role of hydrogen in the reduction of TiO₂

Rutherford backscattering spectrometry (RBS) was used to measure the titanium concentration profile for hydrogen-reduced, vacuum-reduced, and as-received, stoichiometric rutile. These profiles give the degree of reduction, specifically, the extent of oxygen deficiency, as a function of depth below the sample surface. Using forward-recoil spectrometry (FRES), the hydrogen-reduced rutile was found to contain more bulk and near-surface hydrogen than the as-received, stoichiometric rutile. This observation provides additional evidence for a hydrogen-diffusion model for the reduction of rutile in a hydrogen environment.