Hopping and clustering of oxygen vacancies in SrTiO3 by anelastic relaxation

TL;DR

This study investigates the behavior of oxygen vacancies in SrTiO3 using anelastic relaxation, revealing vacancy hopping, pair reorientation, clustering tendencies, and elastic dipole characteristics.

Contribution

It provides new insights into vacancy dynamics, clustering, and elastic properties in SrTiO3 through detailed anelastic relaxation measurements.

Findings

Vacancy hopping barrier of 0.60 eV

Pair reorientation barrier of 1 eV

Evidence of vacancy clustering at low deficiency

Abstract

The complex elastic compliance s11(w,T) of SrTiO3-d has been measured as a function of the O deficiency d < 0.01. The two main relaxation peaks in the absorption are identified with hopping of isolated O vacancies over a barrier of 0.60 eV and reorientation of pairs of vacancies involving a barrier of 1 eV. The pair binding energy is ~0.2 eV and indications for additional clustering, possibly into chains, is found already at d ~0.004. The anistropic component of the elastic dipole of an O vacancy is Deltalambda = 0.026.