Synthesis and properties of the TTA/Gd₂O₃: Eu³⁺ luminescent system

Hybrid materials based on lanthanide ions or lanthanide-doped nanostructured particles have received a lot of recent attention because organic ligands can sensitize RE ions via the “antenna effect.” With the aim of obtaining efficient emission via Eu³⁺ions, luminescent hybrid powders of Gd₂O₃:Eu³⁺ were decorated with thenoyltrifluoroacetone (TTA) by the sol–gel method. This article reports on the influence of the organic ligand on the luminescent properties by varying the TTA: Gd₂O₃:Eu³⁺ molar ratios: X:1 (X = 0.08, 0.16, 0.32, and 0.48). The precursors used to elaborate the TTA/Gd₂O₃:Eu³⁺ hybrid systems were gadolinium and europium nitrates, with ethanol used as a solvent. Gd₂O₃:Eu³⁺, modified nanopowders were previously synthesized by the sol–gel process and heat-treated at 800 °C in the presence of Pluronic F-127; this fact was due to the observed enhanced luminescence intensity promoted by Pluronic F-127. For all of the hybrid systems, the x-ray diffraction results showed a Gd₂O₃:Eu³⁺-TTA cubic structure, without structural changes. FTIR studies revealed the presence of new bands besides those related to Gd–O, which suggests that Gd₂O₃:Eu³⁺ was successfully capped by TTA. The TTA/ Gd₂O₃:Eu³⁺ hybrid systems presented a stronger luminescence intensity than those of the non-hybrid systems; this effect is due to an energy transfer from the 2-thenoyltrifluoroacetone ligands to the Gd₂O₃:Eu³⁺ particles. In this study, the effect of TTA on the structural, morphological, and luminescence properties of TTA/ Gd₂O₃:Eu³⁺ hybrid systems was investigated. [Figure not available: see fulltext.]