Z. Naturforsch. 68a, 605 – 609
Theoretical Studies on the Local Structure and Electron Paramagnetic Resonance Parameters for Cu2+ Centers in TiO2 with one Oxygen Vacancy Adjacent
School of Physics and Electronic Information, Shangrao Normal University, Shangrao Jiangxi 334000, P. R. China
Received November 26, 2012 / revised April 9, 2013 / published online June 12, 2013
Based on the defect model that the impurity Cu2+ in TiO2 on the octahedral Ti4+ site is associated with one oxygen vacancy VO along the C2 axis, the electron paramagnetic resonance (EPR) parameters, i. e., the g factors gi (i = x, y, z) and the hyperfine structure constants Ai, of the Cu2+–VOcenter in TiO2 are calculated by using the perturbation formulas of these parameters for a 3d9 ion in a rhombically elongated octahedra. From this study, the impurity Cu2+ is found to be away from VO by a distance Δz
(≈0.33 Å) along the C2 axis, meanwhile the four O2– ions in the plane perpendicular to the C2 axis may be shifted by Δx (≈0.28 Å) towards VO due to the electrostatic interaction between these ions and VO. The theoretical results based on the above local structure distortions show good agreement with the experimental data.
Key words: Electron Paramagnetic Resonance (EPR); Defect Structures; Cu2+; Oxygen Vacancies (VO); TiO2.