Local Coordination, Influence on Synthesis and Luminescent Features of Eu³⁺ Ions in SiO₂–Poly(methyl methacrylate) Hybrid Materials

Abstract

Because of the tunability of properties demonstrated by organic−inorganic hybrid materials, they have attracted considerable attention in recent years. However, despite luminescence being one of the major research topics involving hybrids, SiO 2 −poly(methyl methacrylate) (PMMA) systems have been poorly explored. In this paper, Eu 3+ :SiO 2 −PMMA samples were prepared with different Eu 3+ /Si molar ratios in order to determine Eu 3+ local coordination, the potential interferences of these ions on synthesis reactions and the optimized lanthanide concentration for improved luminescence output. Careful analysis of FTIR spectra showed the presence of Eu 3+ ions coordinated to carbonyl groups in the hybrid matrix, while TG results, allied to FTIR, indicate dopant influence on the mechanisms of formation of polymeric chains. Photoluminescence results showed that, at higher lanthanide contents, the position of the 5 D 0 → 7 F 0 band and spectroscopic parameters are modified, a clear signal of the formation of lanthanide clusters, which results in concentration quenching of luminescence.

Spectroscopic analysis of Eu3+ doped silica–titania–polydimethylsiloxane hybrid ORMOSILs

“…Furthermore, the 5 D 0 / 7 F 0 transition is narrow which conrms that the Eu 3+ ions occupy asymmetric sites in the host matrix which is a characteristic of amorphous hybrid samples. 26 The 5 D 0 / 7 F 1 transition is a magnetic dipole transition while the 5 D 0 / 7 F 2 transition is an electric dipole transition. Hence the 5 D 0 / 7 F 1 transition does not depend on local environment of the Eu 3+ ions while the 5 D 0 / 7 F 2 transition is affected by the local surroundings of the Eu 3+ ions and the nature of the ligands in the host matrix.…”