Berlin 2018 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 33: Poster Session III

HL 33.38: Poster

Wednesday, March 14, 2018, 17:30–19:30, Poster F

The Effect of Oxygen Vacancies on the Creation and Migration of Ti Interstitials in r-TiO2 — •Julian Gaberle and Alexander Shluger — University College London, WC1E 6BT London, UK

Titanium dioxide finds a wide range of applications from catalysis, electronics, gas sensing to paint. Its broad range of uses is due to its exceptional physical properties i.a. high refractive index, high dielectric and hardness. In its stoichiometric form TiO₂ is a wide bandgap insulator. However, defects and impurities can create states, which lie in the bandgap, thus altering its physical properties. Understanding these defect states is imperative to building new technologies and other future applications.

The two most important defects in TiO₂ are oxygen vacancies and titanium interstitials. Both defects create a defect state just below the conduction band. This defect state is commonly attributed to the formation of polarons on titanium sites, creating a Ti³⁺ species.

In this work, we used ab initio methods to investigate the interplay between oxygen vacancies and Ti interstitials. It was found that the barrier for Frenkel defect formation is significantly reduced in the presence of O vacancies. Furthermore the diffusion barrier of Ti interstitials is dependent on the degree of reduction.