Surface diffusion on SrTiO3 (100): A temperature accelerated dynamics and first principles study

• Published in: Surface science Vol. 617; pp. 237 - 241
• Main Authors: Hong, Minki, Wohlwend, Jennifer L., Behera, Rakesh K., Phillpot, Simon R., Sinnott, Susan B., Uberuaga, Blas P.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.11.2013; Elsevier
• Subjects: Charge transfer; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Diffusion barriers; Empirical analysis; Exact sciences and technology; Migration; Migration energy; nuclear (including radiation effects), defects, mechanical behavior, materials and chemistry by design, synthesis (novel materials), synthesis (scalable processing); Physics; SrTiO3; Strontium titanates; Surface diffusion; Temperature accelerated dynamics; Titanium; Titanium dioxide; SrTiO3; Surface diffusion; Migration energy; Temperature accelerated dynamics; Inorganic compounds; Transition element compounds; Strontium titanates; Diffusion; SrTiO
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2013.08.002

Temperature accelerated dynamics (TAD) with an empirical potential is used to predict diffusion mechanisms and energy barriers associated with surface diffusion of adatoms and surface vacancies on (100) SrTiO3 (STO). Specifically, Sr, O, and Ti adatoms and vacancies are investigated on each termination – SrO and TiO2 – of the SrTiO3 surface. We find that the empirical potential predicts different surface mobility of adatoms depending on the surface termination: they are mobile with relatively low diffusion barriers on the SrO-terminated surface, whereas they are largely immobile on the TiO2-terminated surface. One important finding is that, of the two binding sites on the SrO-terminated surface, one is typically very close in energy to the saddle point. Thus, one of the two sites is a good estimator of the migration energy of the adatom, a conclusion supported by select density functional theory (DFT) calculations. Motivated by this result, we calculate the migration energies for a number of metal elements on the SrO-terminated surface: Ti, Ba, La, and Al. The DFT results also reveal that the details of the migration mechanism depend on the charge state of the diffusing species and that the ability of the empirical potential to properly estimate the migration mechanism depends on the magnitude and variability of the charge transfer between the adatom and the surface. •The diffusion mechanisms of adatoms and vacancies on SrTiO3 (001) were examined.•Surface terminations are important for determining diffusion mechanisms.•Total energy difference of binding sites can be used to estimate migration energies.•The accuracy of empirical potentials depends on the nature of charge transfer.