A quantitative microkinetic model is constructed for the injection of oxygen interstitial atoms from the rutile TiO2(110) surface into the bulk. The underlying rate expressions resemble conventional Langmuir kinetics to describe a gas-surface interaction, with numerical parameters determined through a global optimization procedure applied to a set of self-diffusion profiles from isotopic exchange experiments with a labeled gas. Key activation barriers for the interstitial were found to be 2.4 eV for injection, 0.65 eV for hopping diffusion, and 0.2 eV for exchange with the lattice. The standard formation enthalpy for the (-2) ionization state is 3.7 eV, which decreases to 1.1 eV for the experimental n-type material in equilibrium.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films