α-NaYb(Mn)F₄:Er³⁺/Tm³⁺@NaYF₄ UCNPs as “Band-Shape” Luminescent Nanothermometers over a Wide Temperature Range

Abstract

Novel flower-like α-NaYb(Mn)F4:Er(3+)/Tm(3+)@NaYF4 upconversion nanoparticles (UCNPs) as luminescent nanothermometers have been developed by combining liquid-solid solution hydrothermal strategy with thermal decomposition strategy. Under 980 nm excitation, they exhibit intense upconversion luminescence and temperature-dependent upconversion luminescence over a wide temperature range. The influence of temperature on "band-shape" upconversion luminescence (UCL) spectra and the intensity of emission bands are analyzed and discussed in detail. We further successfully test and verify that intensity ratios REr of (2)H11/2 → (4)I15/2 and (4)S3/2 → (4)I15/2 and RTm of (1)G4 → (3)H5 and (3)H4 → (3)H6 are sensitive to temperature, and the population of active ions follows Boltzmann-type population distribution very well. These luminescent nanothermometers could be applied over a wide temperature range from 123 to 423 K with high sensitivity, which enable them to be excellent candidates for temperature sensors.

Temperature dependent NIR emitting lanthanide-PMO/silica hybrid materials

“…43 A higher temperature induces a higher phonon density, increases multiphonon relaxations, and additionally the energy transfer processes from the ligands to the Ln 3+ ions are strengthened. 44 We believe the temperature dependent luminescence trend where the emission of the sample increases at higher temperature can originate in a large part from the Ln 3+ β-diketonate component. As we have presented in the ESI (Fig.…”

Dually functioned core-shell NaYF4:Er3+/Yb3+@NaYF4:Tm3+/Yb3+ nanoparticles as nano-calorifiers and nano-thermometers for advanced photothermal therapy

“…In fact, the temperature sensing of lanthanide ions has been widely studied 45,59–61 . To further evaluate the temperature sensing performance of the designed core-shell structure, the relative sensitivities for the naked core, core-shell structure and the bulk NaYF 4 :Er 3+ /Yb 3+ were calculated in the temperature region from 300 to 340 K by using the data obtained in this work and our previous work 60 .…”

Ultrahigh-sensitive optical temperature sensing based on quasi-thermalized green emissions from Er:ZnO

“…On the other hand, opposite trend (multiphonon relaxation dominent) for other bands is observed due to thermal quenching. 34 The intensity of 565 nm band decreases rapidly with tempearute and is very low at 493 K. The intensity of 540 nm also decreases beyond 493 K which is believed to be the depletion of population transfer from lower to higher level (Fig. S4).…”

“…31 In this regard, Er 3+ is the most studied RE material for FIR based sensing with fluorides, chalcogenides glasses and ceramics as host materials. [32][33][34][35][36][37] Fluorides are not environmental friendly as toxicity level of fluorides is harmful to living beings and also not promising in terms of physical, chemical and thermal stability. Moreover, the ceramic hosts are composed of different elements, which are synthesized by tedious ceramic synthesis process.…”

“…As the temperature is increased, phonon density increases that favors multiphonon asisted population tranfer from 4 S3/2 to 2 H11/2 due to low separation gap and establishes a quasi-thermal equlibrium between the two bands. 34 This thermally agitated electrons along with direct exited electrons favors radiative trasitions to ground state ( 4 I15/2) causing an increase in intensity with temperature. On the other hand, opposite trend (multiphonon relaxation dominent) for other bands is observed due to thermal quenching.…”