Thermal and pump power effect in SrMoO4:Er3+-Yb3+ phosphor for thermometry and optical heating

Frequency upconversion based thermally stable molybdate phosphors in temperature sensing probe

Er3+-Yb3+ co-doped NaGd(MoO4)2 phosphors with different concentrations of Er3+ and Yb3+ ions have been successfully synthesized via a high-temperature solid-state reaction method. Phase confirmation and morphological studies have been done...

Sextuple ratiometric thermometry based on 980-nm-upconverted green fluorescence of Er3+ ions in submicron crystals

980-nm-upconverted 530 and 550 nm Er³⁺ green fluorescence spectra of Er³⁺/Yb³⁺-codoped NaGd(WO₄)₂ submicron crystals were measured in the temperature range of 298-383 K. A sextuple ratiometric thermometry is proposed. It is established on the basis of six schemes of fluorescence intensity ratio (FIR) that considers three component peaks of the 530 nm emission band and two component peaks of the 550 nm emission band, which involve electronic transitions between two Stark sublevels of Er³⁺. The study shows that the phosphor shows strong green fluorescence, which is verified by measured quantum yield, and thermally stable spectral structure desired for the sextuple ratiometric thermometry. All of the six FIR schemes display highly efficient sensing performances with slightly different thermal sensitivities. Each scheme gives a temperature value and the six schemes give an averaged result. In parallel, we have also carried out an ex vivo experimental study on the temperature characteristics of the green fluorescence of the phosphor. Almost same results have been obtained, verifying biological applicability of the phosphor. The ex vivo experimental results also show that the sextuple thermometry increases considerably the accuracy and reliability of temperature measurement in comparison with the conventional intensity integration method.

Sensitivity improvement induced by thermal response behavior for temperature sensing applications

Overcoming the restriction of the energy gap (700-800 cm-1) in Er3+-doped upconversion (UC) materials to achieve high detection accuracy is crucial for practical temperature detection applications. Herein, we design a feasible route based on the different thermal response behaviors of various hosts to enhance the SA value in a double perovskite NaLaMgWO6:Er,Mo system. The maximum SA value is 222.8 × 10-4@423 K in the NLMW:5%Er3+ host, and this can be promoted to 275.4 × 10-4 K-1@323 K in the NaLaMgWO6:Er,Mo system. The SR values decrease monotonously as the temperature rises, and this is due to the dependency of the SR values on the energy gap. A mechanism that is ascribed to the different thermal response behaviors of the various hosts is proposed, and this mechanism is further proved by investigating the temperature sensing properties of barium gadolinium zincate phosphors that possess the same thermal response behaviors. In addition, this study introduces the idea that a host with a high emission intensity for the 2H11/2 level and a lower emission intensity for the 4S3/2 level is highly suitable for temperature measurements. A thorough investigation of this system offers a strategy to acquire a high SA value and reveals the broad prospects of NaLaMgWO6:Er,Mo in the temperature detection field.

Effects of Tm3+ concentration on upconversion luminescence and temperature-sensing behavior in Tm3+/Yb3+:Y2O3 nanocrystals

The effects of Tm³⁺ concentration on upconversion emission and temperature-sensing behavior of Tm³⁺/Yb³⁺:Y₂O₃ nanocrystals were investigated. Blue and red emissions were observed under 980 nm excitation. Both upconversion emissions and the blue to red intensity ratio were found to decrease with increasing Tm³⁺ concentration. The temperature-sensing performances of the samples were studied, the fluorescence intensity ratio of ¹G_4(a)→³H₆ (477 nm) and ¹G_4(b)→³H₆ (490 nm) transitions from Tm³⁺ ions was chosen as the thermometric index. The results showed that the sensor sensitivity was sensitive to Tm³⁺ ion concentration. The maximum sensitivity of ~32 × 10^-4 K^-1 was obtained for 0.1%Tm³⁺/5%Yb³⁺:Y₂O₃ nanocrystals at 344 K. Moreover, a marked optical induced heating effect was also found in the nanocrystals. The prepared Tm³⁺/Yb³⁺:Y₂O₃ nanocrystals could be used in temperature-sensing probes and in optical heaters.

Investigation of photoluminescence properties, Judd–Ofelt analysis, luminescence nanothermometry and optical heating behaviour of Er3+/Eu3+/Yb3+:NaZnPO4 nanophosphors

The Er³⁺/Eu³⁺/Yb³⁺:NaZnPO₄ nanophosphors can be used as temperature sensors and optical nano-heaters with significant sensor sensitivity.

Synthesis and characterization of SrSnO3 doped with Er3+ for up-conversion luminescence temperature sensors

The present work shows the results of the synthesis of SrSnO₃:Er³⁺ (doped from 0% to 7% with Er³⁺) prepared using a sol–gel method.