Enhancing the Relative Sensitivity of V5+, V4+ and V3+ Based Luminescent Thermometer by the Optimization of the Stoichiometry of Y3Al5−xGaxO12 Nanocrystals

Abstract

In this work the influence of the Ga3+ concentration on the luminescent properties and the abilities of the Y3Al5−xGaxO12: V nanocrystals to noncontact temperature sensing were investigated. It was shown that the increase of the Ga3+ amount enables enhancement of V4+ emission intensity in respect to the V3+ and V5+ and thus modify the color of emission. The introduction of Ga3+ ions provides the appearance of the crystallographic sites, suitable for V4+ occupation. Consequently, the increase of V4+ amount facilitates V5+ → V4+ interionic energy transfer throughout the shortening of the distance between interacting ions. The opposite thermal dependence of V4+ and V5+ emission intensities enables to create the bandshape luminescent thermometr of the highest relative sensitivity of V-based luminescent thermometers reported up to date (Smax, 2.64%/°C, for Y3Al2Ga3O12 at 0 °C). An approach of tuning the performance of Y3Al5−xGaxO12: V nanocrystals to luminescent temperature sensing, including the spectral response, maximal relative sensitivity and usable temperature range, by the Ga3+ doping was presented and discussed.

A Theoretical Framework for Ratiometric Single Ion Luminescent Thermometers—Thermodynamic and Kinetic Guidelines for Optimized Performance

“…[63] Finally, other currently attractive and sensitive (especially lifetimebased) thermometers employ the luminescent 3d 3 ions Cr 3+ [64][65][66][67][68][69][70] or Mn 4+ [71][72][73][74][75][76] in symmetric fluorides or oxides and are based on a 2 E → 4 T 2 (in cubically symmetric crystal fields) thermally induced nonradiative crossover at higher temperatures that lead to a strong decrease of the 2 E-related luminescence decay time. [77] The usage of thermal coupling between states of simultaneously present transition metal ions with different oxidation states has also been presented by Marciniak et al [78,79] Recently, also the unusual ion Mn 5+ has attracted attention for that purpose. [80] Optical (nano)thermometry has shown high potential in the experimental elucidation of several thermodynamic phenomena at the nanoscale and its superiority over, e.g., thermographic methods, which can only measure surface temperatures.…”

“…[ 77 ] The usage of thermal coupling between states of simultaneously present transition metal ions with different oxidation states has also been presented by Marciniak et al. [ 78,79 ] Recently, also the unusual ion Mn 5+ has attracted attention for that purpose. [ 80 ]…”

Deep red upconversion photoluminescence in Er3+‐doped Yb3Ga5O12 nanocrystalline garnet

“…The n value is, however, reduced from three-photon process in Yb 14.99 Er 0.01 Ga 25 O 60 to two-photon UCPL process in the Yb 14.9 Er 0.1 Ga 25 O 60 garnet, as may be seen in Figure 7. The reduction of n value in Figure 7 from n ≈ 2.3 to n ≈ 2.0 with increasing Er 3+ concentration in Yb 15−x Er x Ga 25 O 60 garnets may be explained either by the decrease of the EBT rate due to decreasing overall Yb 3+ concentration, 32 or by the presence of an additional Er 3+ ↔Er 3+ energy transfer or CR processes such as Er 3+ : 4 S3 and Table 1 is prolonged from τ 2 ≈ 10.4 to ≈11.3 ms from x ≈ 0.01 to 0.1 at.% Er 3+ in Yb 15−x Er x Ga 25 O 60 , for which may be responsible the CR2 process increasing the population at the Er 3+ : 4 I 13/2 and the Er 3+ : 4 I 9/2 energy levels (see Figure 6). The increase of the population at the Er 3+ : 4 I 13/2 energy level may satisfactorily explain the Er 3+ : 4 I 13/2 → 4 I 15/2 lifetime prolongation at the relatively low-to-moderate Er 3+ doping level in Yb 15−x Er x Ga 25 O 60 for 0.01 < x ≲ 0.1.…”

Optical Characteristics and Applications of AIE Racemic C6-Unsubstituted Tetrahydropyrimidines

“…Fluorescent temperature probes have the advantages of ultra-high sensitivity, fast response, high spatial resolution, safe, and noninvasive detection signal. Different kinds of fluorescent thermometers have been developed (Wang et al, 2013;Li et al, 2014;Wu1 et al, 2017;Qin et al, 2018;Kniec et al, 2019;Gao et al, 2020;Meng et al, 2020;Back et al, 2021;Wang et al, 2021). However, conventional fluorescent thermometers are sensitive only in a narrow temperature range, which limits their application to a certain degree.…”