A Spectroscopic Analysis of Blue and Ultraviolet Upconverted Emissions from Gd₃Ga₅O₁₂:Tm³⁺, Yb³⁺ Nanocrystals

Abstract

The spectroscopic behavior of gadolinium gallium garnet (Gd3Ga5O12, GGG) nanocrystals codoped with 1% each of Tm3+ and Yb3+ prepared via a solution combustion synthesis procedure was investigated. Initial excitation of the codoped nanocrystals with 465.8 nm (into the 1G4 state) showed a dominant blue-green emission ascribed to the 1G4-3H6 transition as well as red and NIR emissions from the 1G4-3F4 and 1G4-3H5/3H4-3H6 transitions, respectively. Excitation at this wavelength (465.8 nm) showed the existence of a Tm3+ --> Yb3+ energy transfer process evidenced by the presence of the 2F5/2-2F7/2 Yb3+ emission in the NIR emission spectrum. The decay time constants proved that the transfer of energy occurred via the 3H4 state. Following excitation of the Yb3+ ion with 980 nm, intense upconverted emission was observed. Emissions in the UV (1D2-3H6), blue (1D2-3F4), blue-green (1G4-3H6), red (1G4-3F4), and NIR (1G4-3H5/3H4-3H6) were observed and were the direct result of subsequent transfers of energy from the Yb3+ ion to the Tm3+ ion. Power dependence studies showed a deviation from expected values for the number of photons involved in the upconversion thus indicating a saturation of the upconversion process. An energy transfer efficiency of 0.576 was determined experimentally.

Oxide phosphors for light upconversion; Yb3+ and Tm3+ co-doped Y2BaZnO5

“…7(b), Table S1 supplemental material 26 ] due to the back-energy transfer between Tm 3þ and Yb 3þ , depopulating Tm 3þ3 H 4 at high Yb 3þ concentration. 35 The Yb 3þ emission around 1022 nm is also observed under selective Tm 3þ excitation at 790 nm (Fig. S2, supplemental material 26 ), corroborating the presence of such back-energy transfers.…”

Lanthanide upconversion luminescence at the nanoscale: fundamentals and optical properties

“…3a 83 ) . The energy transfer in this case is facilitated by the nonradiative, phonon-assisted processes, where the energy mismatch is compensated by simultaneous emission or absorption of one or more phonons by the host lattice.…”

Nanopartikel für die Aufwärtskonversion

“…[54, 56, 57, 64, 65, 71, 82, 84, 85, 87-92, 94-96, 98, 105, 127, 128, 167, 180, 181, 190, 197-199, 202, 205, 209, 219, 220, 256, 262, 278, 296-332] Dabei wurde eine Vielzahl von Materialklassen untersucht, darunter binäre [82,94,167,180,181,197,199,305] und ternäre Oxide, [85,198] Phosphate, [64] Vanadate, [84] Molybdate, [278] Titanate, [88] Zirconate, [314] Silicate, [56,312] Hydroxide [57,333] und Oxysulfide. [197,333,334] 2003 haben wir erstmals die Photonen-UC in transparenten Kolloiden beschrieben.…”