On the photoluminescence behavior of samarium-doped strontium titanate nanostructures under UV light. A structural and electronic understanding
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2010-01-01
Autores
Longo, Valeria Moraes [UNESP]
Sampaio Costa, Maria das Graca [UNESP]
Simões, Alexandre Zirpoli [UNESP]
Viana Rosa, Ieda Lucia
Paiva Santos, Carlos Oliveira [UNESP]
Andres, Juan
Longo, Elson [UNESP]
Varela, José Arana [UNESP]
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Royal Soc Chemistry
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A combined experimental and theoretical investigation on the photoluminescence properties of SrTiO(3) (ST) and SrSm(0.01)Ti(0.99)O(3) (ST_Sm) nanostructures is presented in this work. The nanocrystalline powders were prepared by the polymeric precursor method, and the order-disorder behavior of this material was investigated by means of X-ray diffraction (XRD), spectral absorbance (UV-vis), transmission electron microscopy (TEM) images, electron paramagnetic resonance (EPR) and photoluminescence (PL) experimental techniques. The decrease in the broad PL emission band of ST and ST_Sm powders measured at room temperature indicates an increase in the structural order as the annealing temperature increases, i.e. characteristic samarium peaks intensify as the structural order increases in ST_Sm samples. The interactions of the network clusters that form the ST and ST_Sm structures were evaluated by means of the ab initio periodic method at the density functional theory (DFT) level with the hybrid nonlocal B3LYP approximation. The symmetry-breaking process that leads to the presence of non-ideal [TiO(6)] and [SrO(12)] clusters, as well as the relationship between these clusters, provides favorable structural and electronic conditions for the appearance of PL phenomena.
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Physical Chemistry Chemical Physics. Cambridge: Royal Soc Chemistry, v. 12, n. 27, p. 7566-7579, 2010.