Hydrothermal synthesis, morphology control and tunable luminescence properties of AgTbW2O8:Eu3+ phosphors

Abstract

Monoclinic AgTbW₂O₈:Eu³⁺ crystals were prepared by a simple one-step hydrothermal method. The phase, morphology and luminescence properties of the obtained phosphors were systematically characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and photoluminescence (PL). The effects of solution pH, W/Tb molar ratios and reaction temperatures as well as reaction times on the size and morphology of the final products were discussed, and the possible formation mechanism of the almond-like structure was proposed. The down-conversion luminescence properties and energy transfer behavior of the AgTbW₂O₈:Eu³⁺ phosphors were studied under ultraviolet light excitation. The emission lights were obtained from green to yellow-green to yellow to red by setting different ratios of Tb³⁺/Eu³⁺. The temperature-dependent fluorescence test data showed that AgTbW₂O₈:Eu³⁺ phosphors have good temperature stability. In addition, by doping alkali metal ions Li⁺, Na⁺, and K⁺ in AgTbW₂O₈:Eu³⁺ phosphors, it is found that the luminescence intensity of phosphors doped with alkali metal ions is enhanced compared with that of phosphors without alkali metal ions, and the phosphor doped with K⁺ has the largest luminescence intensity, which is due to the introduction of K⁺ making the crystal field produce the greatest asymmetry.