Formation and down/up conversion luminescence of Ln3+ doped NaY(MoO4)2 microcrystals

Abstract

NaY(MoO₄)₂ microcrystals with different morphologies including spherical, rhombic, sheet-like, and rectangular plate-like morphologies have been successfully synthesized via a simple hydrothermal method by varying the molar ratios of Y(NO₃)₃/Na₂MoO₄ and pH values of the resultant solutions. NaY(MoO₄)₂ was demonstrated to be a good host material for different lanthanide ions. In the up-conversion luminescence spectrum of NaY(MoO₄)₂:Yb³⁺/Er³⁺ under 980 nm excitation, the green emissions (²H_11/2/⁴S_3/2 → ⁴I_15/2) were observed and the red emission (⁴F_9/2 → ⁴I_15/2) almost disappeared. The CIE chromaticity coordinates of NaY(MoO₄)₂:Yb³⁺/Er³⁺ were calculated to be (0.27, 0.65). In the up-conversion luminescence spectrum of NaY(MoO₄)₂:Yb³⁺/Tm³⁺, the ¹G₄ → ³H₆ as well as ³F₃ → ³H₆ emission was observed and the CIE chromaticity coordinates of NaY(MoO₄)₂:Yb³⁺/Tm³⁺ were calculated to be (0.25, 0.24). The down-conversion luminescence properties of NaY(MoO₄)₂:Eu³⁺ were studied in detail. In addition, the decay lifetimes at the ⁴S_3/2 (Er³⁺), ¹G₄ (Tm³⁺), and ⁵D₀ (Eu³⁺) states were determined to be 5.63 μs, 19.76 μs, and 487.39 μs, respectively.