Optical characteristics of the Eu3+–β-diketonate complex doped into epoxy resin

Abstract

Preparation of epoxy resins doped with triaquatris(acetylacetonate)europium(III) [Eu(ACAC)3(H2O)3] at 1%, 5%, 10% and 15% and their luminescent properties in the solid state are reported. In addition, the catalytic properties of samples doped with [Eu(TTA)3(H2O)2] (I) and [Eu(ACAC)3(H2O)3] (II) have been compared to that of a physical mixture of epoxy resin containing dicyandiamide (III) in the DSC curing process under heating. It was verified that the product (I) was cured under the same conditions as (III), but that product (II) was not cured. The compounds were characterized by elemental analysis, thermogravimetry (TG), differential scanning calorimetry (DSC) and infrared spectroscopy. The emission spectra of the Eu3+-ACAC complex doped in the epoxy resin recorded at 298 and 77K exhibited the characteristic bands arising from the 5D0→7FJ transitions (J=0–4). The experimental intensity parameter, Ω2, indicated that the Eu3+ ion in the precursor complex is in a more polarizable chemical environment than in the doped system. The emitter 5D0 level lifetimes for doped samples (1%, 5%, 10% and 15%) show the luminescence decay curve profiles as single exponentials. The Eu-doped system containing the TTA ligand presented a higher emission quantum efficiency than that with ACAC. The emission quantum efficiencies (η) are also discussed.