Journal of Alloys and Compounds 374 (2004) 101–104 Synthesis, characterization, and luminescent properties of MCM-41 and AlMCM-41 mesoporous materials containing Eu(III) ions Joana M.F.B. Aquino, Antonio S. Araujo ∗ , Dulce M.A. Melo, José E.C. Silva, Marcelo J.B. Souza, Ant ˆ onio O.S. Silva Department of Chemistry, Federal University of Rio Grande do Norte, PDCEM, CP 1662, CEP 59078-970 Natal-RN, Brazil Abstract Nanostructured materials such as MCM-41 modified with rare earth ions have been studied due to their potential for a variety of applications. Rare earth trivalent ions in some solid compounds emit light at characteristic wavelengths due to infra 4f or inter 4f–5d transitions. The MCM-41 and AlMCM-41 mesoporous materials were synthesized by hydrothermal treatment using cethyltrimethylammonium as template, and then calcined at 500 ◦ C in presence of air. The obtained materials were impregnated with Eu(III) ions using europium nitrate solution in ethanol with equivalent concentrations of 5, 10, and 15% in mass, followed by calcination at 500 ◦ C under nitrogen atmosphere. The Eu-containing products were characterized by thermogravimetric analysis (TGA), X-ray diffraction, and photoluminescence spectroscopy. The emission spectra were recorded at room temperature. For the Eu–MCM-41 and EuAl–MCM-41 samples, intense photoluminescence were observed in the visible region, with maximum intensity centered at 620 nm. © 2003 Elsevier B.V. All rights reserved. Keywords: Mesoporous materials; MCM-41; Europium; Photoluminescence 1. Introduction Since its discovery in 1992 [1,2] MCM-41 has become the most popular member of the M41S family of mesoporous silicate and aluminosilicate materials. The most interesting feature of MCM-41 with its regular pore system consists of an hexagonal array of one-dimensional shaped pores. The pore diameter of MCM-41 can be varied systematically from 2 to 10 nm [2]. Other interesting physical proper- ties of MCM-41 include a highly specific surface of up to 1500 m 2 g -1 , and a specific pore volume of up to 1.3 ml g -1 . Due to its regular structure and pore shape MCM-41 has at- tracted considerable interest as a model substance for a vast range of applications [3,4] in catalysis, sorption, molecular recognition, electronics, and photochemistry. The properties of the MCM-41 materials can be adjusted by isomorphous substitution of Si by a trivalent cation such as Al resulting in the AlMCM-41 mesoporous material. Recently, there has been considerable interest in the incorporation of the rare earth ions in the mesoporous materials for the obtain- ∗ Corresponding author. Tel.: +55-84-211-9240; fax: +55-84-211-9240. E-mail address: asa-ufrn@usa.net (A.S. Araujo). ing of materials active optically. The rare earth trivalent ions in some solid compounds emit light at characteristic wavelengths due to intra 4f or inter 4f–5d transitions [5]. The 4f electrons of the rare earth ions are shielded by the outer 5s and 5p electrons. However, the intensities of 4f–4f transitions depend strongly on the nature and structure of chemical environment around the rare earth ion. This is due to the factor that these lines are forbidden by Laporte’s rule, and therefore their transitions are subject to second-order mechanisms [6,7]. These properties are interesting for the development of new materials with the capability to produce visible light with narrow lines, and crucial by ap- plications in optoelectronic technology as optical memory devices, lasers, fiber amplifiers, and fluorescence matrix as base for new photonic devices applications [8]. The photoluminescence of the Eu(III) ion, in especially, make them potential candidate for use as luminescent material by provides facilities in the interpretation of the spectral data [9–11]. The Eu(III) has a great advantage because it has non-degenerate ground and emitting states and the 5 D 0 → 7 F 0 transition gives information about the site sym- metry of host. This property permits possible application as structural probe of the local environment for technology of new optics sensors. In this report, it is presented the first 0925-8388/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2003.11.075