Molten salt synthesis, characterization, and luminescence of SrWO4, SrWO4:Tb3+ and SrWO4:Eu3+ powders

SrWO4, SrWO4:Tb3+, and SrWO4:Eu3+ powders were synthesized by a method of molten salt. XRD patterns showed that the synthesized powders have a pure tetragonal scheelite structure without the presence of deleterious phases. Scanning electron microscopy images show that powders are in the range of 20-35 nm. The emission spectrum of SrWO4 shows the emission peak in the blue spectral region. The excitation spectra of SrWO4:Tb3+ and SrWO4:Eu3+ show the energy transfer from WO4 (2-) group to Tb3+ and Eu3+ ions with a high efficiency. The emission spectrum of SrWO4:Tb3+ shows the green emission at 545 nm corresponding to the D-5(4) -> F-7(5) transition of Tb3+. The emission spectrum of SrWO4:Eu3+ shows the red emission located at 612 nm corresponding to the D-5(0) -> F-7(2) transition of Eu3+. The asymmetry ratio of SrWO4:Eu3+ is found to be 5.54, which indicates that the Eu3+ ions are located in a lower symmetric site.