The Ti3+ center, based upon a regular Ti site perturbed by an O vacancy (VO), was identified by electron spin resonance in textured films. The center exhibited tetragonal symmetry along cubic <100> axes, with g-factors of g|| = 1.997 and g = 1.904. The spectrum of this defect disappeared after film annealing (700C) in an O2 atmosphere. The observed spectrum was described as being Ti3+–VO couple defects or an F+ center, which had never been observed in bulk BaTiO3. It was concluded that electron spin resonance was a unique tool for identifying O-vacancy related defects.

Electron Spin Resonance Investigation of Oxygen-Vacancy Related Defects in BaTiO3 Thin Films. V.V.Laguta, A.M.Slipenyuk, I.P.Bykov, M.D.Glinchuk, M.Maglione, D.Michau, J.Rosa, L.Jastrabik: Applied Physics Letters, 2005, 87[2], 022903 (3pp)