Dresden 2014 – scientific programme

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DS: Fachverband Dünne Schichten

DS 20: Focus Session: Emerging oxide semiconductors I (jointly with HL, DF, O)

DS 20.5: Talk

Wednesday, April 2, 2014, 10:45–11:00, POT 081

Tailoring the electronic and magnetic structure of doped rutile-TiO₂ using p-elements (C,N); A Hybrid DFT study. — •Jacqueline Atanelov, Christoph Gruber, and Peter Mohn — Vienna University of Technology, Center for Computational Materials Science

We study the electronic and magnetic structure of carbon and nitrogen impurities and interstitials in rutile TiO₂. To this end we perform ab-initio calculations of a 48-atom supercell employing the VASP code. In order to obtain a realistic description of the electronic and magnetic structure, exchange and correlation are treated with the HSE06 hybrid functional. Substitutional carbon and nitrogen are found to have a magnetic moment of 2 and 1µ_B, respectively, with a tendency for anti-ferromagnetic long range order. For C/N on interstitial sites we find that carbon is non-magnetic while nitrogen always possesses a magnetic moment of 1µ_B. We find that these interstitial positions are on a saddle point of the total energy. The stable configuration is reached when both carbon and nitrogen form a C-O and N-O dimer with a bond length close to the double bond for CO and NO. This result is in agreement with earlier experimental investigations detecting such N-O entities from XPS measurements. The frequencies of the symmetric streching mode are calculated for these dimers, which could provide a means for expermental verification. For all configurations investigated both C and N states are found inside the TiO₂ gap. These new electronic states are discussed with respect to tuning doped TiO₂ for the application in photocatalysis.