Preparation, crystal structure and up-conversion luminescence of Er3+, Yb3+ co-doped Gd2(WO4)3

Abstract

Up-conversion (UC) phosphors Gd₂(WO₄)₃:Er³⁺/Yb³⁺ were synthesized by a high temperature solid-state reaction method. The crystal structure of Gd₂(WO₄)₃:3% Er³⁺/10% Yb³⁺ was refined by Rietveld method and it was showed that Er³⁺/Yb³⁺ were successfully doped into the host lattice replacing Gd³⁺. Under 980 nm laser excitation, intense green and weak red emissions centered at around 532 nm, 553 nm, and 669 nm were observed, which were assigned to the Er³⁺ ion transitions of ⁴H_11/2 → ⁴I_15/2, ⁴S_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2, respectively. The optimum Er³⁺ doping concentration was determined as 3 mol% when the Yb³⁺ concentration was fixed at 10 mol%. The pump power study indicated that the energy transfer from Yb³⁺ to Er³⁺ in Er³⁺, Yb³⁺ co-doped Gd₂(WO₄)₃ was a two-photon process, and the related UC mechanism of energy transfer was discussed in detail.