On the photoluminescence behavior of samarium-doped strontium titanate nanostructures under UV light. A structural and electronic understanding.
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.
LIEC, Instituto de Química, Universidade Estadual Paulista, 14800-900, Araraquara, SP, Brasil. valerialongo@liec.ufscar.br
Valéria Moraes
VM
Longo
Maria
M
das Graça Sampaio Costa
Alexandre
A
Zirpole Simões
Ieda Lúcia Viana
IL
Rosa
Carlos Oliveira Paiva
CO
Santos
Juan
J
Andrés
Elson
E
Longo
José Arana
JA
Varela