Controllable synthesis of multi-morphological SrWO4:Ln3+ (Ln = Eu, Tb) hierarchical structures and their luminescence properties

Abstract

Multi-morphological Ln³⁺ (Ln = Eu, Tb) doped SrWO₄ hierarchical structures were successfully synthesized via a hydrothermal method. The phase structure, morphology and luminescence properties of the as-prepared samples were characterized by XRD, SEM, TEM, PL spectroscopy and lifetime measurements. The results indicate that the alteration of synthesis conditions has almost no effect on the phase structure, but has a prominent effect on the morphology of the obtained samples, such as the molar ratio of Sr²⁺ to WO₄²⁻ from 1 : 3 to 6 : 1 (split spheres, dumbbell-like, rod-like, nanosheets), addition of Na₃C₆H₅O₇·2H₂O from 0.1 to 0.5 g (microspheres, rice-like), addition of Na₂EDTA·2H₂O from 0.01 to 0.3 g (spheres, split spheres, peanut-like, drum-like, ellipsoidal morphology), and the doping concentration of Eu³⁺ ions from 1% to 16% (dumbbell-like, rod-like). The as-synthesized SrWO₄:Ln³⁺ (Ln = Eu, Tb) samples with various morphologies have an identical scheelite structure and exhibit the characteristic visible emission of the dopant rare earth ions under the excitation of UV light.