The role of Nd3+ concentration in the modulation of the thermometric performance of Stokes/anti-Stokes luminescence thermometer in NaYF4:Nd3+

Abstract

The growing popularity of luminescence thermometry observed in recent years is related to the high application potential of this technique. However, in order to use such materials in a real application, it is necessary to have a thorough understanding of the processes responsible for thermal changes in the shape of the emission spectrum of luminophores. In this work, we explain how the concentration of Nd3+ dopant ions affects the change in the thermometric parameters of a thermometer based on the ratio of Stokes (4F3/2 → 4I9/2) to anti-Stokes (4F7/2,4S3/2 → 4I9/2) emission intensities in NaYF4:Nd3+. It is shown that the spectral broadening of the 4I9/2 → 4F5/2, 2H9/2 absorption band observed for higher dopant ion concentrations enables the modulation of the relative sensitivity, usable temperature range, and uncertainty of temperature determination of such a luminescent thermometer.

Biocompatible Neodymium-Doped Nanocrystals as Probes for Diffraction-limited,in vitroTemperature Sensing

“…We attribute this higher correlation to improved accuracy as a consequence of larger spectral shifts which results in a relative signal to noise improvement. The observed results show that Nd-NC@shell particles display high sensitivity to temperature changes in the BW-I, and this observation is in agreement with previously reported studies using Nd-doped NaYF4 NCs, which show a similar spectral shape between 850 and 920 nm and a temperature dependent LIR trend characteristic of Nd 3+ in a NaYF4 matrix 40 . Hence the as-synthesized NCs demonstrate clear potential to be used as nanothermometers for NP-HT applications.…”

“…It is theorized that Nd 3+ ions initially undergo the electronic transitions 4 I 9/2 → 4 F 5/2 and 4 I 9/2 → 2 H 9/2 upon NIR excitation. Non-radiative relaxation then brings the system to the metastable 4 F 3/2 state before emission occurs 40 . The PL spectra, and integrated emission between 850 and 920 nm, for all the Nd-NCs, the Nd-NC@shell, and the negative control (NaYF 4 only) with 785 nm excitation are compiled in Figures 4c and 4e, respectively.…”

“…In theory, an increasing dopant concentration should increase PL intensity due to an increase in emitting centers. However, it has been shown that beyond a certain concentration threshold, the shorter distance between Nd 3+ ions in the NaYF 4 lattice promotes non-radiative cross-relaxation described by ( 4 F 3/2 ; 4 I 9/2 ) → ( 4 I 15/2 ; 4 I 15/2 ), which decreases overall PL 29,40,42 . A similar trend was observed upon 808 nm laser excitation (Fig 4d, f).…”

Novel Fluoride Matrix for Dual-Range Optical Sensors and Visualization

“…The sensitivity between 0.5 and 1.5% K -1 at around 300 K is typically for Er 3+ [22]. In the paper [23], it was proposed to use silica coating to expand the thermometry range to 900 • C; the relative sensitivity was from 1.02% K -1 at 300 K to 0.13% K -1 at 900 • C. The use of Nd 3+ ions allows a shift of the operating wavelength range into NIR and obtains a relative sensitivity of 1.1% K −1 for NaYF 4 :0.1%Nd 3+ [24]. For Nd 3+ /Tm 3+ /Yb 3+ /Gd 3+ four-doped NaYF 4 nanoparticles the relative sensitivity was significantly higher and reached 2.89% K −1 in the temperature range of 333-553 K [25].…”