Sonochemical synthesis of hierarchical SrWO₄:Eu³⁺/Bi³⁺ superstructures and tunable luminescence

Abstract

Hierarchical 3D SrWO₄:Eu³⁺/Bi³⁺ superstructures were synthesized by the sonochemical process. The SrWO₄:Eu³⁺/Bi³⁺ phosphors were characterized by XRD, FTIR, SEM, and fluorescence spectrophotometer. The XRD and FTIR results indicated that the samples have the pure tetragonal phase. The SEM images showed that the samples have hierarchical structure composing of lots of similar nanosheets with the thickness of about 20 nm and the width in the range of 0.3–1.5 μm. Under the excitation of 266 nm, SrWO₄:Eu³⁺/Bi³⁺ phosphors showed characteristic emission bands originating from the ⁵D₀ → ⁷F_J (J = 1, 2, 3 and 4) transitions of Eu³⁺ ions. The codoped Bi³⁺ ions highly enhanced the emission intensity of Eu³⁺, suggesting the efficient energy transfer between Bi³⁺ and Eu³⁺. The energy transfer from Bi³⁺ to Eu³⁺ was mainly through exchange interaction which is located at the nearest neighbour lattices.