Controlled synthesis and up/down-conversion luminescence of self-assembled hierarchical architectures of monoclinic AgRE(WO4)2:Ln3+ (RE = Y, La, Gd, Lu; Ln = Eu, Tb, Sm, Dy, Yb/Er, Yb/Tm)

Abstract

Monoclinic AgRE(WO₄)₂ (RE = Y, La, Gd, Lu) with novel self-assembled hierarchical architectures were fabricated via a facile and mild liquid route. The phase and morphology of these products are strongly dependent on the pH of the mixed dispersion. Polyvinylpyrrolidone (PVP) also has a crucial effect on the formation of the hierarchical ellipsoid-shaped structures. The possible formation mechanism was proposed based on the time-dependent experiments. These hierarchical ellipsoids possess a low filling factor and high internal porosity, thus are well suited for applications such as sensors, catalysts and optical devices. In addition, monoclinic AgRE(WO₄)₂ (RE = La, Y, Gd, Lu) exhibit excellent multicolor up/down-conversion (UC/DC) luminescence after incorporating Ln³⁺ (Ln = Eu, Tb, Sm, Dy, Yb/Er, Yb/Tm) cations. Notably, AgLa(WO₄)₂:Eu³⁺ (2 mol%), AgGd(WO₄)₂:Eu³⁺ (2 mol%) and AgY(WO₄)₂:Sm³⁺ (2 mol%) radiate white emission under UV excitation. The quantum yields of AgY(WO₄)₂:Tb³⁺ (95%), AgY(WO₄)₂:Dy³⁺(56%) and AgLa(WO₄)₂:Eu³⁺ (40%) are rather high.