Well-defined sodium gadolinium molybdate microcrystals with diverse morphologies and dimensions: Controllable synthesis, multicolor emissions, and potential applications

Abstract

Abstract A series of tetragonal phase sodium gadolinium molybdate [Na0.5Gd0.5MoO4] microcrystals with diverse particle sizes, morphologies, and dimensions have been fabricated via a mild and controllable hydrothermal approach. The synthesis process is performed under aqueous condition without using any surfactant, organic solvent, or template. The particle size and crystal shape of the hydrothermal products can be controlled by simply changing the feeding molar ratio of reactants or reaction temperature and time. Both the excellent down-conversion and up-conversion luminescence can be realized by incorporating appropriate lanthanide activator ions into the as-obtained Na0.5Gd0.5MoO4 host upon UV or NIR excitation. The calcined Na0.5Gd0.5MoO4:Ln3+ phosphors exhibit stronger emission intensity due to the enhanced crystallinity during the annealing process. Moreover, the dependence of luminescence intensity on different morphologies and performing temperatures of Na0.5Gd0.5MoO4:Ln3+ samples has been also investigated. Finally, the LED devices have been prepared by integrating the as-synthesized phosphors into UV or NIR LED chips, which exhibit dazzling characteristic multicolor emissions of Ln3+ ions under an injection current. Due to their high crystallinity, uniform and well-defined morphology, and eminent luminescence properties, the as-obtained Na0.5Gd0.5MoO4:Ln3+ phosphors may be potentially applied in fields of solid state lightening and optoelectronic devices.