Facile composite synthesis and photoluminescence of NaGd(MoO4)2: Ln3+ (Ln = Eu, Tb) submicrometer phosphors

NaGd(MoO4)2:Ln3+ (Ln = Eu, Tb) submicrometer phosphors have been synthesized by a composite method including the solid state reaction process at room temperature and the hydrothermal process. It is revealed that temperature and humidity have an influence on the reaction rate and that higher temperature and humidity can speed up the reaction process. Crystalline water is necessary for the solid phase reaction at room temperature. The x-ray diffraction (XRD) patterns indicate that NaGd(MoO4)2:Ln3+ (Ln = Eu, Tb) submicrometer phosphors crystallize well with the scheelite structure. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images illustrate that the average grain size of NaGd(MoO4)2:Ln3+ is about 225 nm without conglomeration. The luminescent lifetime and quantum efficiency for NaGd(MoO4)2:Eu3+ are determined.