Electron Spin Resonance on Rutile (TiO2) with Cobalt Ions Combined with Oxygen Vacancies

Electron spin resonance of Co 2+ ions in rutile was investigated in detail. Weak signals with eight hyperfine structure were observed apart from signals associated with the regular substitutional Co 2+ ions. There were three groups of weak signals whose signals whose signal intensities varied by reduction of oxygen in rutile. It was concluded that, from symmetry relation of the resonance pattern and variation of the signal intensity due to reduction degree of oxygen in rutile, three groups of the weak signals associated with the substitutional Co 2+ ions combined with the nearest and the second neighbour oxygen vacancies.