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Combined Experimental and Theoretical Study to Understand the Photoluminescence of Sr 1- x TiO 3- x

2004; American Chemical Society; Volume: 108; Issue: 26 Linguagem: Inglês

10.1021/jp048877y

1520-6106

Emmanuelle Orhan, F. M. Pontes, M. Anicete-Santos, E. R. Leite, A. Beltrán, Juán Andrés, T. M. Boschi, P.S. Pizani, José Manuel Rey Varela Rey Varela, Carlton A. Taft, E. Longo,

Perovskite Materials and Applications

A joint experimental and theoretical study has been carried out to rationalize the results of visible photoluminescence measurements at room temperature on Sr1-xTiO3-x (ST) perovskite thin films. From the experimental side, ST thin films, x = 0 to 0.9, have been synthesized following soft chemical processing, and the corresponding photoluminescence properties have been measured. First principles quantum mechanical techniques, based on density functional theory at the B3LYP level, have been employed to study the electronic structure of a crystalline, stoichiometric (x = 0) ST-s model and a nonstoichiometric (SrO-deficient, x ≠ 0) and structurally disordered ST-d model. The relevance of the present theoretical and experimental results of the photoluminescence behavior of ST is discussed. The optical spectra and the calculations indicate that the symmetry-breaking process on going from ST-s to ST-d creates electronic levels in the valence band. Moreover, an analysis of the Mulliken charge distribution reveals a charge gradient in the structure. These combined effects seem to be responsible for the photoluminescence behavior of deficient Sr1-xTiO3-x.