Triple-temperature readout in luminescence thermometry with Cr³⁺-doped Mg₂SiO₄ operating from cryogenic to physiologically relevant temperatures

Abstract

Cr3+-doped Mg2SiO4 orthorhombic nanoparticles are synthesized by a combustion method. The 3d3 electron configuration of the Cr3+ ion results in the deep-red emission from optical transitions between d–d orbitals. Two overlapping emissions from the Cr3+ spin-forbidden 2Eg→ 4A2g and the spin-allowed 4T2g→ 4A2g electronic transitions are influenced by the strong crystal field in Mg2SiO4 and, thus, are suitable for ratiometric luminescence thermometry. The temperature-induced changes in Cr3+-doped Mg2SiO4 emission are tested for use in luminescence thermometry from cryogenic to physiologically relevant temperatures (10–350 K) by three approaches: (a) temperature-induced changes of emission intensity; (b) temperature-dependent luminescence lifetime; and (c) temperature-induced changes of emission band position. The second approach offers applicable thermometry at cryogenic temperatures, starting from temperatures as low as 50 K, while all three approaches offer applicable thermometry at physiologically relevant temperatures with relative sensitivities of 0.7% K−1 for emission intensity, 0.8% K−1 for lifetime and 0.85% K−1 for band position at 310 K.

Al2O3 co-doped with Cr3+ and Mn4+, a dual-emitter probe for multimodal non-contact luminescence thermometry

“…The application of single ions of Cr 3+ or Mn 4+ for triple temperature readout has been recently demonstrated. 29,32 Here we test the multimodal dual-emitter approach by co-doping Al 2 O 3 with both these ions. Aluminium oxide is a stable material with simple structure and is comprehensively characterised as temperature sensor based on luminescence (see ref.…”

“…29 Materials doped with transition metal ions are well suited for multimodal sensing owing to a noticeable shift of the luminescence peaks with temperature, caused by electron-phonon interaction of impurity ions with the host lattice. [30][31][32]…”

Dual-emission luminescence thermometry using LaGaO3:Cr3+, Nd3+ phosphors

“…11,22,23,24,25 The Boltzmann equilibrium between the closely separated 2 E and 4 T2 excited states of d 3 ions such as Cr 3+ underpins them. [26][27][28][29] The aim of the present study was to combine the complementary advantages of lanthanide and transition metal ions in the design of a luminescent thermometer that would function in the near-infrared (NIR) region. The neodymium(III) ion was selected for investigation with Cr 3+ , as Nd 3+ not only emits in the NIR but also has a number of excited states of energies that overlap with the emission of Cr 3+ , allowing for Cr 3+ -to-Nd 3+ energy transfer.…”

Structurally induced tuning of the relative sensitivity of LaScO3:Cr3+ luminescent thermometers by co-doping lanthanide ions

“…Transition metal (TM) ions have significantly higher absorption cross sections due to a stronger coupling to local vibrational odd-parity modes and are investigated to a much lower extent in the context of LT. In contrast to the 4f-4f transitions of the Ln 3+ ions, the spectroscopic properties of the TM ions such as emission and absorption wavelength are influenced by the locally surrounding ligand field of the ions This allows to optimize the thermometric performance of these luminescent ions and tailor it with respect to the practical requirements [14,[21][22][23][24][25][26][27][28][29][30][31][32]. This is especially well manifested in the case of Cr 3+ ions [22,27,28,[30][31][32][33].…”

“…It was reported that an increase in concentration of Cr 3+ ions (30% Cr 3+ in Y3Al2Ga3O12, 50% in Y3Al5O12 and Y3Ga5O12, respectively) caused a statistical elongation of the metal-oxygen distances, which led to a decrease in the crystal field strength [28]. This unique feature of the Cr 3+ ions has been used by many authors to develop highly sensitive ratiometric luminescent thermometers using two operating strategies: (i) based on the intensity ratio of the narrow 2 E(g) → 4 A2(g) and broad 4 T2(g) → 4 A2(g) bands [14,22,[30][31][32] and (ii) based on the change in that respective intensity ratio with respect to an internal luminescent reference like Ln 3+ ion, whose luminescence is not affected within the regarded temperature range [25,27,28,41,42]. It is usually found that the relative sensitivities are higher upon comparison of the temperature evolution of the general Cr 3+ -based luminescence compared to the lanthanide-based luminescence than upon simple exploitation of thermal coupling between the 2 E(g) and 4 T2(g) states of Cr 3+ alone.…”