The complex elastic compliance s11(ω,T) of SrTiO3−δ was measured as a function of the O deficiency δ < 0.01. The 2 main relaxation peaks in the absorption were identified with hopping of isolated O vacancies over a barrier of 0.60eV and reorientation of pairs of vacancies involving a barrier of 1eV. The pair binding energy was ≈0.2eV, and indications for additional clustering, possibly into chains, was found already at δ ~ 0.004. The anisotropic component of the elastic dipole of an O vacancy was Δλ = 0.026. The possible role of electrostatic repulsion between vacancies in slowing the kinetics for their aggregation was considered.

Hopping and Clustering of Oxygen Vacancies in SrTiO3 by Anelastic Relaxation. F.Cordero: Physical Review B, 2007, 76[17], 172106