Enhancement of luminescence properties and thermal stability of Sr2(Y, La)NbO6:Dy3+ phosphors by crystal lattice substitution engineering

Sr 2 (Y, La)NbO 6 :Dy blue-white phosphors were prepared by high-temperature solid-state method. The effects of substitution on the crystal structure, photoluminescence properties, and thermal stability were investigated by XRD, SEM, EDS, XPS, diffuse reflectance spectroscopy, and photoluminescence spectroscopy. Phase analysis indicates that the crystal structure of the host materials is not altered by the introduction of Dy 3+ ion, but transfers from monoclinic to cubic system by substituting Y 3+ ions with La 3+ ions. Morphological analysis reveals that the phosphors exhibit irregular shapes with the particle diameters ranging from 10 μm to 20 μm. The blue shift appears in the charge transfer band with the increase of La 3+ ion dosage. Sr 2 (Y, La)NbO 6 :Dy phosphors can be excited by near-ultraviolet and blue light. The emission spectra exhibit two characteristic peaks at 488 nm and 580 nm, corresponding to the 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 optical transitions of Dy 3+ ions, respectively. The emission intensity and the fluorescence lifetime are enhanced by the replacement of Y 3+ ions with La 3+ ions. The Sr 2 LaNbO 6 :Dy phosphor possesses excellent thermal stability. The luminescent intensity at 423 K retains 83% of the value at room temperature. The result indicates that Sr 2 (Y, La)NbO 6 :Dy phosphors have good prospects in solid state lighting.