Journal of Solid State Chemistry 171 (2003) 412–419 Optical characteristics of the Eu 3+ –b-diketonate complex doped into epoxy resin Duclerc F. Parra, a Adriana Mucciolo, a Hermi F. Brito, a, and Larry C. Thompson b a Departamento de Quı´ mica Fundamental, Instituto de Quı´ mica, Universidade de Sa˜o de Paulo, C.P. 26077, Sa˜o Paulo-SP, Brazil b Department of Chemistry, University of Minnesota, Duluth, Duluth MN 55812, USA Received 26 April 2002; received in revised form 15 July 2002; accepted 23 July 2002 Abstract Preparation of epoxy resins doped with triaquatris(acetylacetonate)europium(III) [Eu(ACAC) 3 (H 2 O) 3 ]at1%,5%,10%and15% and their luminescent properties in the solid state are reported. In addition, the catalytic properties of samples doped with [Eu(TTA) 3 (H 2 O) 2 ] (I) and [Eu(ACAC) 3 (H 2 O) 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 Eu 3+ -ACAC complex doped in the epoxy resin recorded at 298 and 77K exhibited the characteristic bands arising from the 5 D 0 - 7 F J transitions (J ¼ 024). The experimental intensity parameter, O 2 ; indicated that the Eu 3+ ion in the precursor complex is in a more polarizable chemical environment than in the doped system. The emitter 5 D 0 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 (Z) are also discussed. r 2003 Elsevier Science (USA). All rights reserved. Keywords: Epoxy resin; Trivalent europium; b-Diketonate; Polymerization; Photoluminescence 1. Introduction The epoxy structure of the diglycidylether of bi- sphenol-A (DGEBA) allows the creation of epoxide networks by ring opening polymerization. A variety of cross-linking agents known as hardeners or catalysts that promote self-polymerization are reported [1]. The catalytic activity of trivalent rare-earth (RE 3+ ) triflates inthepolymerizationofepoxyresinofdiglycidyletherof bisphenol A has been discussed in Refs. [2,3]. These RE 3+ compounds promote the ring opening of oxiranes and induce the thermal cross-linking process. In a recent study [4] the europium b-diketonate complex [Eu(TTA) 3 (H 2 O) 2 ], was used to dope epoxy resin at proportions of 1%, 5% and 10% (where TTA=thenoyltrifluoroacetonate). These systems were synthesized at around 601C. The photoluminescence properties were described for the epoxy compounds doped with the Eu 3+ –b-diketonate. The TTA anion has electron-withdrawing capacity. This characteristic al- lows the rare-earth ions to coordinate to the epoxide oxygen weakening the C–O bond as described in the literature for the compounds of rare-earth triflates [5,6]. The [Eu(ACAC) 3 (H 2 O) 3 ] complex has been used as a precursor in the preparation nanophase of europium oxide polycrystalline thin films deposited on Si sub- strates [7]. Synthesis and luminescence properties of Eu 3+ –b-diketonate complexes incorporated into solid matrices have been studied [8]. The luminescent properties of rare-earth complexes with various organic ligands have been reported in the literature [9–16]. In particular, the employment of rare- earth ions in display technologies plays an important role in optical electronic devices [17]. The trivalent europium ion has advantageous photoluminescent properties for the complex: narrow emission bands (4f 24f transitions forbidden by the Laporte rule) leading to monochromatic red emission color; the main excited state is the emitter 5 D 0 level separated around of  Corresponding author. Fax: +55-11-3815-5579. E-mail address: hefbrito@iq.usp.br (H.F. Brito). 0022-4596/03/$-see front matter r 2003 Elsevier Science (USA). All rights reserved. doi:10.1016/S0022-4596(02)00223-2