Ho,Yb:KLu(WO₄)₂ Nanoparticles: A Versatile Material for Multiple Thermal Sensing Purposes by Luminescent Thermometry

Abstract

We studied the temperature dependence of the up-conversion emission in the green and the red regions of the electromagnetic spectrum of Ho,Yb:KLu(WO 4 ) 2 nanocrystals after excitation at 980 nm, and analyzed their possible applications as thermal sensors in luminescence thermometry in the RT to 673 K range, by using different techniques. The different thermometric techniques used arethe fluorescence intensity ratio technique of two thermally coupled Stark sublevels, the intensity ratio between the red and green luminescence bands generated by two electronically and thermally linked manifolds of these nanoparticles, lifetime measurements, or by observing the change of the color of the emitted light arising from the sample. In all cases, thermal sensitivities comparable to those previously reported in the literature are obtained, but offering different thermal sensing approaches using a single material, providing a way to corroborate the temperature measurements.

Simple experimental procedures to distinguish photothermal from hot-carrier processes in plasmonics

“…More suitable label-free techniques exist, such as Raman spectroscopy 75 or fluorescence anti-Stokes emission 76 of the metal nanoparticles themselves. The use of NV centers or lanthanide-doped nanoparticles 77,78 may also give reliable measurements, as these are chemically inert and thermally robust. However, when collective thermal effects are dominant (see also the discussion in the next section), small-scale temperature measurements are not relevant, as the temperature distribution is uniform throughout the sample at the macroscale, despite the nanoscale nature of the heat sources.…”

Nanothermometry: From Microscopy to Thermal Treatments

“…[23] Typical UCNPs are composed of ah ost crystal, such as metal fluorides (NaYF 4 ), oxides (Y 2 O 3 ), phosphates (YPO 4 ), and vanadates (GdVO 4 ) doped with lanthanide ions, either individually (Er 3 + ,Y b 3 + , Ho 3 + ,G d 3 + ,T m 3 + )o rw ith their combinations. [23] Typical UCNPs are composed of ah ost crystal, such as metal fluorides (NaYF 4 ), oxides (Y 2 O 3 ), phosphates (YPO 4 ), and vanadates (GdVO 4 ) doped with lanthanide ions, either individually (Er 3 + ,Y b 3 + , Ho 3 + ,G d 3 + ,T m 3 + )o rw ith their combinations.…”

“…Another interesting class of materials extensively tested for nanothermometry is based on UCNPs. [23] Typical UCNPs are composed of ah ost crystal, such as metal fluorides (NaYF 4 ), oxides (Y 2 O 3 ), phosphates (YPO 4 ), and vanadates (GdVO 4 ) doped with lanthanide ions, either individually (Er 3 + ,Y b 3 + , Ho 3 + ,G d 3 + ,T m 3 + )o rw ith their combinations. [24] An example of the mechanism for two-step upconversion of the Er 3 + ,Yb 3 + /NaYF 4 NPs is shown in Figure 2.…”

Visible‐Light Excited Luminescent Thermometer Based on Single Lanthanide Organic Frameworks

“…In the last years, a new paradigm has emerged for temperature measurement based on luminescent thermal probes that are minimally invasive or even noninvasive, combining high accuracy and fast response with high spatial resolution and the possibility of tracking fast‐moving objects . Among the various possibilities of assessing the temperature from luminescence features (peak energy, steady‐state emission intensity of one, or two transitions, and the lifetime or risetime of an excited state) the most popular approaches in lanthanide (Ln 3+ )‐based systems use the emission intensity of a pair of transitions or the lifetime of an excited state. Since measuring the luminescence lifetime requires a relatively long time and a postprocessing computational treatment, the intensity‐based approach is more reliable in real‐time temperature measurements .…”