The role of structural disorder on luminescence of Eu-doped Na0.5Bi0.5TiO3.

A detailed analysis of photoluminescence of Eu-doped Na0.5Bi0.5TiO3 (NBT) is performed using it as a tool for describing the local structure of NBT. The obtained results reveal the low symmetry of the Eu3+ local environment in NBT, as indicated by the observed maximal number of sublevels of the 5D0→7F1 and the 5D0→7F2 luminescence transitions, clearly observed at low temperatures. Approximation of the luminescence spectra by Gaussian peaks provides valuable information about the shift of the involved levels upon change of the excitation wavelength. Variation in the strength of the crystal field in Eu-doped NBT is evaluated. Temperature dependence of the luminescence above room temperature is analyzed for the poled and the unpoled states of the material. The results obtained for Eu-doped NBT are compared with the results for Er-doped NBT reported previously. [ABSTRACT FROM AUTHOR]