Hydrothermal Synthesis and Luminescent Properties of Spindle‐Like NaGd(MoO 4 ) 2 :Eu 3+ Phosphors

Abstract Spindle‐like NaGd(MoO 4 ) 2 : Eu 3+ phosphors with various Eu 3+ concentrations were prepared via a hydrothermal process and characterized using X‐ray diffraction (XRD) and field emission scanning electron microscopy (FE‐SEM). The XRD results suggested that the prepared samples had a scheelite structure. The FE‐SEM images indicated that the prepared NaGd(MoO 4 ) 2 : Eu 3+ phosphors were spindle‐like. The influences of the ratio of sodium citrate and the rare earth cations on the product were studied. It was found that sodium citrate, as the chelating agent, could significantly influence the structure and morphology of the samples. The emission spectra, excitation spectra, fluorescence decay curves, and quantum yields of the samples were measured. The luminescent properties of the materials were studied. The results indicated that the electron–phonon coupling between the Eu 3+ and the NaGd(MoO 4 ) 2 host was weak, and with the increase of the Eu 3+ concentration, the Huang–Rhys factor increased. Additionally, the quantum efficiency of the Eu 3+ 5 D 0 level was calculated, and it was found that the quantum efficiency decreased with the increase of the Eu 3+ concentration.