Controllable synthesis and tunable luminescence properties of Y2(WO4)3: Ln3+ (Ln = Eu, Yb/Er, Yb/Tm and Yb/Ho) 3D hierarchical architectures

Yttrium tungstate precursors with novel 3D hierarchical architectures assembled from nanosheet building blocks were successfully synthesized by a hydrothermal method with the assistance of sodium dodecyl benzenesulfonate (SDBS). After calcination, the precursors were easily converted to Y-2(WO4)(3) without an obvious change in morphology. The as-prepared precursors and Y-2(WO4)(3) were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra, respectively. The results reveal that the morphology and dimensions of the as-prepared precursors can be effectively tuned by altering the amounts of organic SDBS and the reaction time, and the possible formation mechanism was also proposed. Upon ultraviolet (UV) excitation, the emission of Y-2(WO4)(3):x mol% Eu3+ microcrystals can be tuned from white to red, and the doping concentration of Eu3+ has been optimized. Furthermore, the up-conversion (UC) luminescence properties as well as the emission mechanisms of Y-2(WO4)(3):Yb3+/Ln(3+) (Ln = Er, Tm, Ho) microcrystals were systematically investigated, which show green (Er3+, S-4(3/2), H-2(11/2) -> I-4(15/2)), blue (Tm3+, (1)G(4) -> H-3(6)) and yellow (Ho3+, S-5(2) -> I-5(8)) luminescence under 980 nm NIR excitation. Moreover, the doping concentration of the Yb3+ has been optimized under a fixed concentration of Er3+ for the UC emission of Y-2(WO4)(3):Yb3+/Er3+.