Synthesis and optical characterization of trivalent europium doped M_4Al_2O_9 (M = Y, Gd and La) nanomaterials for display applications

摘要

A series of aluminate phosphors M_4Al_2O_9:Eu~(3+) (M = Y, Gd and La) exhibiting red color under UV excitation was synthesized with combustion process. The concentration of dopant ion used was 0.03 moles in these lattices. The precursors were explored at 600 °C using urea as fuel. However, the well-defined crystalline phase of the respective phosphors was obtained at temperature above 900 °C. The luminescent properties of prepared materials were studied by photoluminescence spectroscopy. The materials were found to emit intense red color owing to characteristic ~5D_0→~7F_2 (forced electric dipole) transition occurring at 608-612 nm. Some weak emission peaks also existed in photoluminescence spectra due to ~5D_0→~7F_1 (magnetic dipole) transition observed at 591-593 nm and ~5D_0→~7F_3 transition located at 652-655 nm. The crystal structure and phase purity of the prepared materials was analyzed using X-ray diffraction study. XRD spectra of europium(III) doped Y_4Al_2O_9 phosphor showed monoclinic structure with space group P21/c. Gd_4Al_2O_9:Eu~(3+) phosphor confirmed single phased monoclinic crystal structure having space group Pnam. Structure and bonding in these phosphors were studied with Fourier transform infrared spectroscopy. Transmission electron micrographs showed their three dimensional structure and estimated particle size was found in nano range (20-50 nm) making these phosphors suitable hosts for various display device applications.