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The contactless real-time temperature sensing technique with high temporal and spatial resolution is in high demand for the countless applications. Here, the Yb3+/Er3+−codoped GeO2–PbO–PbF2 glass ceramics synthesized via the melt-quenching technique has been presented as an optical thermometer. The thermal sensing was designed based on the temperature dependent fluorescence intensity ratios of thermally (2H11/2 and 4S3/2) and non-thermally (2H11/2 and 4F9/2) coupled Er3+ levels. The ratiometric techniques provide the thermal sensing within the temperature range of 300–466 K. The absolute and relative thermal sensitivities as well as the temperature resolution were calculated and compared with other Yb3+/Er3+-doped materials. The temperature of the microelectronic component on the printed circuit board was defined using the optical thermometry as a proof of concept revealing Yb3+/Er3+−codoped GeO2–PbO–PbF2 phosphor to be a promising candidate for precise non-contact thermal sensor.

In this work, we report on Nd3+-doped Y2O3 nanocrystalline powders synthesized by standard Pechini and combined Pechini-foaming method. The structural and luminescence properties of nanocrystalline powders were studied using XRD, SEM, Raman and photoluminescence spectroscopy. Doping concentration effect on the luminescence intensity and lifetime of Y2O3:Nd3+ nanophosphors was investigated in detail. The optimum doping concentration of Nd3+ ions in yttria host was determined to be 1 at.%. Steady-state and kinetics photoluminescence properties of starting nanocrystalline powder and ceramics obtained with hot pressing were measured and discussed.

We report on Lu2(WO4)3: Yb3+, Tm3+ upconversion nanoparticles prepared via modified Pechini method, which is low-cost in comparison with analogs and allows achieving the homogenous rare earth ions (Yb3+ and Tm3+) dispersion in the host matrix. The Tm3+ doping concentration effect on structural and luminescence properties has been studied in detail. The structure of the nanoparticles was characterized by XRD and Raman spectroscopy. Both analytical methods confirmed the formation of single phase Lu2(WO4)3: Yb3+, Tm3+ nanoparticles without any impurities. It was found that thulium ions are uniformly incorporated into the tungstate structure up to a concentration of 1%. SEM images showed that prepared samples consisted of weakly agglomerated nanoparticles with an average size of about 40–80 nm. Emission and excitation spectra of all Lu2(WO4)3: xTm3+, 10% Yb3+ samples contained characteristic transitions inside Tm3+ ions. Upconversion spectra demonstrated intense infrared line (3H4–3H6) as well as weak blue 1G4–3H6 and two red (1G4–3F4, 3F2,3–3F6) bands obtained upon 974 nm excitation. Optimal Tm3+ doping concentration was found to be 0.3% for both 3H4–3H6 and 1G4–3F4 transitions. Change of chromaticity coordinates along with Tm3+ amount increase was also observed.

Rare earth-doped materials are successfully utilized as non-contact optical temperature sensors. Thermal sensing is usually based on the ratiometric technique between two separate emission lines originated from thermally-coupled levels. We study Gd2O3:Eu3+ 1 at.% and YAG: Eu3+ 4 at.% phosphors as luminescence thermometers in 298–473 K range using both conventional experimental and Judd-Ofelt based theoretical approaches. Thermometric performances of suggested sensors were quantified through absolute and relative thermal sensitivities and temperature resolution. Experiment and theoretical modelling gave similar results. This proves the theoretical model as a simple and fast method for estimation of the Eu3+-doped thermometer perspectives.

Ce3+-doped apatites have been synthesized by precipitation method in the range of the Ce/Ca atomic ratio in solutions from 0.05 to 5%. Obtained precipitates were studied with X-ray powder diffraction, infrared spectroscopy, scanning electron microscopy, EDX and luminescence spectroscopy. Cerium content in the synthesized apatites reaches 0.33 apfu (Ce/Ca = 3.9%). Relations between Ce content in the solution and precipitate have been established. It was revealed that during synthesis Ce-monazite starts to precipitate as a secondary phase at 1% Ce/Ca ratio in starting solution. Doping concentration effect on the luminescence intensity and lifetime of HAp:Ce3+ nanophosphors was studied in detail. Optimum doping concentration of Ce3+ ions in hydroxyapatite host was determined to be 0.3% of the Ce/Ca atomic ratio, which corresponds to 0.5% of the Ce/Ca ratio in the starting solution. The luminescence quenching occurs through energy transfer among the nearest neighbor Ce3+ ions.

Nanocrystalline Eu3+-doped YAG powders were prepared by modified Pechini method. The structural properties were investigated with XRD, SEM and Raman spectroscopy. XRD pattern indicated that the phase-pure YAG:Eu3+ crystallites were obtained without the formation of any other phases. Raman spectrum revealed good homogeneity and crystallinity of synthesized nanopowders. The luminescent properties were studied by measurement of excitation and emission spectra, quantum yields and decay curves. The effect of Eu3+ concentration on 5D0 level lifetime was studied. The processes resulting in the relaxation of excited state (5D0 level) were discussed and the probabilities of radiative and nonradiative processes were calculated using the model of f–f transition intensities. It was found that the observed shortening of 5D0 level lifetime with Eu concentration is caused by increase of nonradiative process probability.