A series of novel red tungsto-molybdate phosphors, LiEu1 xSmx(WO4)0.5(MoO4)1.5 (x = 0, 0.25%, 0.50%, 0.75%, 1.00%, 2.00%, 4.00%, 6.00%, 8.00% and 10.00%), were synthesized using conventional solid state reaction methods. The experimental results indicate that the introduction of Sm3+ changes neither the crystal structure nor the shape and position of the emission spectra. However, it extends the excitation region at 400 nm and enhances the emission at 615 nm. The reason for the improvement of red emission of Eu3+ by the introduction of Sm3+ and the energy transfer mechanism from Sm3+ to Eu3+ was investigated in detail.
Based on a hydrothermal method, the Ce3+/Tb3+ co-doped Ba Gd F5 nanocrystals were synthesized by controlling the introduction concentration of Ba2+ and Gd3+. The samples were characterized by X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM) images, photoluminescence(PL) excitation, and emission spectra, as well as the photoluminescence dynamic decay curves. With the increase of the Ba2+ concentration in the synthesis procedure, the positions of diffraction peaks of XRD patterns move toward lower degree, and the case of the samples synthesized with the increase of the Gd3+ concentration is contrary, which consists well with each other. The FE-SEM images suggest that the BaGdF5 nanocrystals are in spherical morphology,and the average diameters decrease with the increase of Ba2+ or Gd3+ concentration. For the 4f–5d transition of Ce3+ is sensitive to the environment of local lattice, the PL excitation and emission spectra of the samples are different. The 4f–4f transition of Tb3+ also presents different optical properties in different host lattices. The variations of the optical properties of Ce3+ and Tb3+ as well as the lifetime of the 5D4+7F5 emission of Tb3+ are also consistent well with each other in the two series of samples.
