Comparative studies of upconversion luminescence and optical temperature sensing in Tm³⁺/Yb³⁺ codoped LaVO₄ and GdVO₄ phosphors

Abstract

Tm3+/Yb3+ codoped LaVO4 and GdVO4 phosphors are successfully synthesized using solid state reaction methods and then upconversion emission studies are performed.

Assessment of NIR-triggered PEG-coated NaGdF4:Tm3+/Yb3+ bio-compatible upconversion nanoparticles for contrast enhancement in OCT imaging and optical thermometry

“…Previous reports show the occurrence of various types of energy transfer processes viz. cooperative energy transfer and cross relaxation processes in Tm 3+ /Yb 3+ doped systems which is realized in this case as well [38,39]. Ideally, the emission of 451 nm requires three-photon absorption processes but here due to the cross-relaxation process, the emission occurs resulting from the absorption of two photons.…”

Achieving high-sensitivity dual-mode optical thermometry via phonon-assisted cross-relaxation in a double-perovskite structured up-conversion phosphor

“…The Tm 3+ ions in the 3 H 6 low level can be directly excited to the 1 G 4 level after receiving the energy transferred from the Yb 3+ ions in the virtual energy level. 41,42 Another part of Yb 3+ ions at the excitation energy level 2 F 5/2 can undergo an energy transfer process with Tm 3+ . Under 980 nm excitation, Yb 3+ ions undergo a transition of 2 F 7/2 + hv (980 nm) → 2 F 5/2 , followed by an energy transfer (ET) process ET1 and resulting in Tm 3+ ions to be excited from the 3 H 6 level to the 3 H 5 level.…”