Synthesis, characterization and luminescent properties of novel red emitting phosphor Li3Ba2Ln3(MoO4)8:Eu3+ (Ln = La, Gd and Y) for white light-emitting diodes

Intense red emitting phosphors Li(3)Ba(2)Ln(3)(MoO4)(8):Eu3+ (Ln= La, Gd and Y) have been prepared by sol-gel method. The crystallization processes of these phosphor precursors have also been characterized by X-ray diffraction (XRD) and thermogravimetry-differential thermal analysis (TG-DTA). The properties of these resulting phosphors are characterized by photoluminescence (PL) spectra and reflectance spectra in a comparable way. In addition, environmental scanning electron microscopy (ESEM) is used to characterize the shape and size distribution of the phosphors. The results of TG-DTA and XRD indicate that all of the Li(3)Ba(2)Ln(3)(MoO4)(8):Eu3+ (Ln = La, Gd and Y) phosphors crystallize completely at about 550 degrees C, and they all adopt the monoclinic structure in the range of our experiments. The luminescent properties of these phosphors are also similar. The excitation (PLE) spectra of phosphors Li(3)Ba(2)Ln(3)(MoO4)(8):Eu3+ (Ln =La. Cd and Y) are mainly attributed to O -> Mo charge-transfer (CT) band at about 295 nm and some sharp lines of Eu3+ transitions in near-UV and visible regions, and the two strongest absorption lines at 395 nm and 465 nm are comparative. For all of Li(3)Ba(2)Ln(3)(MoO4)(8):Eu3+ (Ln = La, Gd and Y) phosphors, intense red emissions peaked at 616 nm assigned to D-5(0) -> F-7(2) transition of Eu3+ are obtained under the excitation of similar to 394 nm and similar to 465 nm light. which indicates that these phosphors may serve as potential red phosphor candidate for near-UV and blue LEDs. (C) 2009 Elsevier B.V. All rights reserved.