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

Abstract

a Up-conversion (UC) phosphors Gd2(WO4)3: Er 3+ /Yb 3+ were synthesized by a high temperature solid-state reaction method. The crystal structure of Gd2(WO4)3: 3% Er 3+ /10%Yb 3+ was refined by Rietveld method and it was showed that Er 3+ /Yb 3+ were successfully doped into the host lattice replacing Gd 3+ . Under 980nm laser excitation, intense green and weak red emissions centered at around 532nm, 553nm, and 669nm were observed, which were assigned to the Er 3+ ion transitions of 4 H11/2→ 4 I15/2, 4 S3/2→ 4 I15/2 and 4 F9/2→ 4 I15/2, respectively. The optimum Er 3+ doping concentration was determined as 3mol% when the Yb 3+ concentration was fixed at 10mol%. The pump power study indicated that the energy transfer from Yb 3+ to Er 3+ in Er 3+ , Yb 3+ co-doped Gd2(WO4)3 was a two-photon process, and the related UC mechanism of energy transfer was discussed in detail.

Multi-color luminescence properties and energy transfer behaviour in host-sensitized CaWO4:Tb3+,Eu3+phosphors

“…Metal tungstates have emerged as an important family of luminescent materials owing to their unique structural, excellent thermal stability and interesting luminescence properties. [29][30][31][32][33] Among them, calcium tungstate (CaWO 4 ) is a selfactivated phosphor that can emit a high-efficiency blue emission when excited by ultraviolet light, which due to the tetrahedral WO 4 2À groups in the host lattices. 34,35 The luminescent properties of CaWO 4 and rare earth ions doped CaWO 4 have been described a few years ago.…”

Features of the Phase Preferences, Long- and Short-Range Order in Ln2(WO4)3 (Ln = Gd, Dy, Ho, Yb) with Their Relation to Hydration Behavior

“…As it can be seen from Figure 8b, there are virtually no change in the FT-IR spectra of Gd 2 (WO 4 ) 3 for annealing temperatures raised from 700 • C to 1000 • C, which strongly implies that the oxygen sublattice is successfully formed already at 700 • C. The vibrational peaks at around 728 cm −1 and 860 cm −1 are assigned to the O-W-O stretching modes of the WO 2− 4 tetrahedron. The 418 cm −1 and 460 cm −1 bands can be attributed to the stretching vibrations of the W-O bonds [52]. It is of note that the FT-IR peaks revealed in the spectra of the well-crystallized Gd 2 (WO 4 ) 3 -1000 • C sample are assigned to the tetrahedral W(1)O 4 and W(2)O 4 units in La 2 (WO 4 ) 3 , which crystallizes in the monoclinic structure (sp.…”