Synthesis and Luminescence Properties of Eu2+-Doped Sr3MgSi2O8 Blue Light-Emitting Phosphor for Application in Near-Ultraviolet Excitable White Light-Emitting Diodes

Abstract

In this study, [Sr_0.99Eu_0.01]₃MgSi₂O₈ phosphors were sintered at 1200-1400 °C for 1-5 h by using the solid-state reaction method. The crystallinity and morphology of these phosphors were characterized through X-ray diffraction analysis and field-emission scanning electron microscopy, respectively, to determine their luminescence. The photoluminescence properties, including the excitation and emission properties, of the prepared phosphors were investigated through fluorescence spectrophotometry. The α-Sr₂SiO₄, Sr₂MgSi₂O₇, and Sr₃MgSi₂O₈ phases coexisted in the [Sr_0.99Eu_0.01]₃MgSi₂O₈ phosphors, which were synthesized at low temperatures. The particles of these phosphors had many fine hairs on their surface and resembled Clavularia viridis, which is a coral species. Transmission electron microscopy and energy dispersive X-ray spectroscopy indicated that the fine hairs contained the Sr₂SiO₄ and Sr₂MgSi₂O₇ phases. However, when the [Sr_0.99Eu_0.01]₃MgSi₂O₈ phosphors were sintered at 1400 °C, the Sr₃MgSi₂O₈ phase was observed, and the Eu²⁺-doped Sr₃MgSi₂O₈ phase dominated the only broad emission band, which had a central wavelength of 457 nm (blue light). The emission peaks at this wavelength were attributed to the 4f⁶5d¹-4f⁷ transition at the Sr²⁺(I) site, where Sr²⁺ was substituted by Eu²⁺. The average decay time of the synthesized phosphors was calculated to be 1.197 ms. The aforementioned results indicate that [Sr_0.99Eu_0.01]₃MgSi₂O₈ can be used as a blue-emitting phosphor in ultraviolet-excited white light-emitting diodes.

Keywords: Eu2O3; Sr3MgSi2O8; blue emission; phosphor.