Communication pubs.acs.org/IC
Synthesis and Photoluminescence Properties of Ca2Ga2SiO7:Eu3+ Red Phosphors with an Intense 5D0 → 7F4 Transition Gaganpreet Kaur Behrh, Romain Gautier, Camille Latouche, Stéphane Jobic, and Hélène Serier-Brault* Institut des Matériaux Jean Rouxel, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3, France S Supporting Information *
luminescence for WLEDs has been published.13 However, to date no investigation has been reported about the luminescence properties of Eu3+-doped Ca2Ga2SiO7. Thus, this paper presents an analysis of the luminescence properties of Eu3+-doped Ca2Ga2SiO7 with intense 5D0 → 7F2 (∼610 nm) and 5D0 → 7 F4 (∼700 nm) emissions. The samples Ca2−3x/2EuxGa2SiO7 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) were synthesized using a solid-state reaction technique at high temperature. The starting materials CaCO3 (analytical reagent, A.R.), Ga2O3 (A.R.), SiO2 (A.R.), and Eu2O3 (99.99%, Alfa Aesar) were weighted according to the chemical formulas of the target products Ca2−3x/2EuxGa2SiO7. The stoichiometric reactants were mixed and ball-milled in ethanol at 700 rpm for 4 h. Then the mixtures were heated at 1350 °C for 24 h in air to lead to white powder. The compound Ca2Ga2SiO7 belongs to the melilite family with the space group P42̅ 1m (No. 113; a = 7.793 Å and c = 5.132 Å14). This structure is built upon a regular tetrahedral site fully occupied by Ga3+ and a much distorted tetrahedral site in which Si4+ and Ga3+ are randomly distributed. In this framework, the Ca2+ cations are located in an 8-fold-coordinated site called a Thomson cube. According to the results presented in Figure 1, all of the obtained samples crystallized in the melilite (ICSD file 027428). When the Eu3+ concentration exceeded 5%, a detailed analysis of the patterns showed very weak diffraction peaks at 31.8° and 32.1°, indicating the appearance of an unidentified impurity phase. Because of similar ionic radii in an 8-fold
ABSTRACT: Novel melilite-type Ca2Ga2SiO7:Eu3+ redemitting phosphors with different Eu3+ contents were synthesized via high-temperature solid-state reaction. The crystal structure, optical absorption, and photoluminescence properties were investigated, while density functional theory calculations were performed on the host lattice. The excitation spectra indicate that phosphors can be effectively excited by near-UV light for a potential application in white-light-emitting diodes. Because of the abnormally high intensity emission at about 700 nm arising from the 5D0 → 7F4 transition of Eu3+, the phosphors Ca2Ga2SiO7:Eu3+ show a deep-red emission with chromaticity coordinates (0.639, 0.358).
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hite-light-emitting diodes (WLEDs) have been attracting much attention because of their considerable impact on issues such as energy consumption and the environment. Therefore, WLEDs are thought to have brought a revolution in energy-efficient lighting and are promising to replace conventional light sources such as incandescent and fluorescent lamps in the near future.1,2 The most common approach to obtain white light is to employ the yellow-emitting YAG:Ce3+ phosphor and blue InGaN chips. Unfortunately, the drawbacks of this method are a low color rendering index (
