Nanocrystalline samples were prepared by using a sol-gel technique, and X-ray measurements showed that the grain size ranged from 26 to 120nm. A blue photoluminescence band was observed at about 470nm at room temperature. An investigation of the dependence of the visible emission band upon annealing temperature and grain size showed that grain size and dielectric confinement played important roles, and that O vacancies could act as the radiative centres which were responsible for the observed emission band. The luminescence mechanism was explained in terms of self-trapped excitons.

Roles of Defects and Grain Sizes in Photoluminescence of Nanocrystalline SrTiO3. W.F.Zhang, Z.Yin, M.S.Zhang, Z.L.Du, W.C.Chen: Journal of Physics - Condensed Matter, 1999, 11[29], 5655-60