Synthesis and upconversion emission studies of CaYF₅:Ho³⁺/Yb³⁺ phosphor and its applications in optical thermometry, fingerprint detection, and security ink

Abstract

In this work, a CaYF5:Ho3+/Yb3+ upconversion phosphor was synthesized and its structural, morphological, and optical properties were studied. Apart from these studies, latent fingerprint detection and security ink applications were also demonstrated using this phosphor.

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

“…This variation in emission intensity exhibits an inverse relationship, as an increase in temperature corresponds to a reduction in emission intensitya phenomenon commonly referred to as 'thermal quenching.' Numerous previously published reports have illustrated this decrease in UC emission intensity, which is attributed to the heightened occurrence of non-radiative relaxation processes in ions as temperature rises [37,43,44].…”

“…Understanding the UC mechanism in the Tm 3+ /Yb 3+ system requires knowing how many NIR pump photons are involved in the UC emission process. Using the well-known relationship between excitation pump power (P laser ) and UC emission intensity (I UC ), which is given by equation 1 [37] I UC ∝ P n laser .…”

A green light emissive LaSr2AlO5:Er3+ nanocrystalline material for solid state lighting: crystal phase refinement and down-conversion photoluminescence with high thermal stability

“…Depending on the direct transition, indirect transition, forbidden direct, and forbidden indirect transitions, the value of n may be 1/2, 2, 3, and 3/2, respectively. Eqn (15) and (16) may be used to write the following expression 58 [ F ( R ) hν ] 2 = C ( hν − E g ) n …”

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

“…NTCLs-based FIR technique, opposed to TCL-based FIR technique, is not restricted by difference in energy levels and may thus have better temperature sensitivity. 30,31 Herein, monoclinic LaVO 4 : Tm 3+ /Yb 3+ and tetragonal GdVO 4 : Tm 3+ /Yb 3+ phosphors were synthesized via conventional solid-state reaction method for comparison of upconversion emission and non-contact temperature sensitivity in the temperature range 300-653 K under 980 nm laser diode excitation. Non-thermally coupled level 3 F 3 and 1 G 4 of Tm 3+ ion are utilized for temperature sensing application in both the phosphors.…”