Controlled synthesis and novel luminescence properties of string SrWO4:Eu3+ nanobeans†
One-dimensional SrWO4:Eu3+ nanostructures were prepared by a hydrothermal method. The structures and morphologies of the nanocrystals were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy. The results indicated that the phase compositions, morphologies and sizes and luminescence properties of SrWO4:Eu3+ are related to the initial reactant content and reaction time, and lower initial reactant content is beneficial for the formation of the string SrWO4:Eu3+ nanobeans. The photoluminescence properties of SrWO4:Eu3+ were investigated in detail. In the emission spectra of SrWO4:Eu3+, the 5D0 → 7F1 is dominant when the excitation wavelength is 295 nm, while the 5D0 → 7F2 is dominant when the excitation wavelengths are in the range of 363–537 nm. Obviously, the string SrWO4:Eu3+ nanobeans have multiple luminescence centers or emitting states. The excitation spectra of SrWO4:Eu3+ contain several sharp peaks attributed to f–f transitions of Eu3+ ions and a broad excitation band assigned to the overlap of WO43− absorption and charge transfer transition between Eu3+ and O2−. The intensity ratio of the broad excitation band to the sharp excitation peaks changed with the emission wavelength as well as the Eu3+ content. In addition, Eu3+ ions occupy higher symmetry sites in SrWO4:Eu3+ nanocrystals with increasing the particle size of nanocrystals. The effect of Tb3+ as well as Gd3+ ions on the photoluminescence of SrWO4:Eu3+ was also investigated.