Vacancy defect positron lifetimes in strontium titanate

The results of positron-annihilation lifetime spectroscopy measurements on undoped, electron-irradiated, and Nb-doped SrTiO3 single crystals are reported. Perfect lattice and vacancy defect positron lifetimes were calculated using two different first-principles schemes. The Sr-vacancy defect-related positron lifetime was obtained from measurements on Nb-doped, electron-irradiated, and vacuum-annealed samples. Undoped crystals showed a defect lifetime component dominated by trapping to Ti vacancy-related defects.