Effect of Hf ⁴⁺ doping on structure and enhancement of upconversion luminescence in Yb:Tm:LiNbO ₃ crystals

Abstract

A series of Yb:Tm:LiNbO 3 crystals doped with x mol% Hf 4+ ions (x = 2, 4, and 6) were grown by the Czochralski method. The dopant occupancy and defect structure of Hf:Yb:Tm:LiNbO 3 crystals were investigated by x-ray diffraction and infrared transmission spectra. The influence of Hf 4+ ions concentration on UV-VIS-NIR absorption spectra of Hf:Yb:Tm:LiNbO 3 crystals was discussed. The upconversion luminescence of Hf:Yb:Tm:LiNbO 3 crystals was obtained under 980 nm excitation. Strong emissions were observed at 475 nm in the blue wavelength range and 651 nm in the red wavelength range. Remarkably, enhancement of the red and blue upconversion luminescence was achieved by tridoping Hf 4+ ions.

Pressure- and temperature-dependent luminescence from Tm3+ ions doped in GdYTaO4

“…In recent years, researches about the spectra of Tm 3+doped materials have been continually intensified for their potential applications. Owing to its rich energy levels, Tm 3+ ion exhibits outstanding up-conversion for near-infrared (NIR) excitations [1][2][3] and down-conversion for ultraviolet (UV) excitations. [4][5][6] With the up-conversion mechanism and the down-conversion mechanism, Tm 3+ -doped materials can generate UV emissions by 1 D 2 → 3 H 6 transition, blue emissions by 1 D 2 → 3 F 4 transition, blue-green emissions by 1 G 4 → 3 H 6 transition, red emissions by 1 G 4 → 3 H 4 and 3 F 2,3 → 3 H 6 transitions, NIR emissions by 3 H 4 → 3 H 6 and 3 F 4 → 3 H 6 transitions, making them valuable for applications in optical display, [1,4,6] optical sensing, [1,6] lighting, [1,4,6] biological labeling, [1][2][3]7] quantum efficiency enhancing for solar cells, [2,4,5] fiber optics, and medical surgery.…”

“…Owing to its rich energy levels, Tm 3+ ion exhibits outstanding up-conversion for near-infrared (NIR) excitations [1][2][3] and down-conversion for ultraviolet (UV) excitations. [4][5][6] With the up-conversion mechanism and the down-conversion mechanism, Tm 3+ -doped materials can generate UV emissions by 1 D 2 → 3 H 6 transition, blue emissions by 1 D 2 → 3 F 4 transition, blue-green emissions by 1 G 4 → 3 H 6 transition, red emissions by 1 G 4 → 3 H 4 and 3 F 2,3 → 3 H 6 transitions, NIR emissions by 3 H 4 → 3 H 6 and 3 F 4 → 3 H 6 transitions, making them valuable for applications in optical display, [1,4,6] optical sensing, [1,6] lighting, [1,4,6] biological labeling, [1][2][3]7] quantum efficiency enhancing for solar cells, [2,4,5] fiber optics, and medical surgery. [8] Rare-earth tantalates with LnTaO 4 (Ln = Y, Gd, La, Sc, Lu) stoichiometry are promising host materials for rareearth activator ions, [9][10][11][12] which have high density and hardness values, [9,13,14] high x-ray and UV absorptions, [11][12][13] high chemical and physical stabilities.…”