Controllable synthesis and luminescent properties of three-dimensional nanostructured CaWO4:Tb3+ microspheres

► Nanostructured CaWO4:Tb3+ microspheres were self-assembled via a sonochemical route with the aid of PEG-600. ► Formation mechanism of the microspheres was proposed based on the ultrasonic irradiation time experiments. ► Energy transfer processes between Tb3+ ions were studied through analysis on the fluorescence decays.