Study on Defects in Fe-Doped SrTiO3 by Positron Annihilation Lifetime Spectroscopy

SrTi1−xFexO3−δ ceramics were prepared using a traditional solid-state reaction method. From X-ray diffraction (XRD) result, we found that the doped Fe3+ dissolved in the lattice, and no secondary phase was observed. Cation vacancies in perovskite oxides were identified via positron annihilation lifetime spectroscopy (PALS) measurements. Undoped and Fe-doped SrTiO3 ceramics and single-crystal SrTiO3 were measured by PALS at room temperature. The results show that the main defects in undoped SrTiO3 ceramics are Ti-related defects, and the isolated Ti vacancy lifetime is about 183.4 ps. With the increase of Fe3+, the concentration of the Ti vacancies decreases accompanied by the appearance of the V″Sr − nV o ∙∙ (defect association of Sr vacancies and multiple O vacancies) vacancy defect complexes.