For the first time, the synthesis, luminescent and structural properties of stable perovskite-type (Cs_1−xRb_x)₄PbBr₆ (R = Cs, Rb) nanocrystals are shown. In the absence of rubidium, Cs₄PbBr₆ and CsPbBr₃ perovskite crystals precipitate in the ZnO–Na₂O–B₂O₃–GeO₂ glass matrix. With ascending rubidium content, the precipitation of (Cs,Rb)₄PbBr₆ nanocrystals is replaced by the Rb₄PbBr₆ nanocrystals nucleation. Nucleated nanocrystals exhibit an intense green luminescence. With an increase of the rubidium content, the luminescence maximum shifts to the blue region, the luminescence quantum yield increases from 28 to 51%, and the average decay time increases from 2 to 8 ns. Several assumptions have been made about the nature of the green luminescence of perovskite-like Cs₄PbBr₆ and (Cs,Rb)₄PbBr₆ crystals in glasses. It is concluded that the most probable cause is the impurity inclusions of CsPbBr₃ and (Cs,Rb)PbBr₃ crystals.

This paper shows the laser irradiation effect on optical characteristics on PbSe chalcogenide films as a result of irreversible structural modification. The features of film structure and property modification under the action of a continuous wave (CW) laser with a 405 nm wavelength and nanosecond laser pulses with a 1064 nm wavelength are studied. The valence and conduction bands boundaries displacement as a laser radiation result of photothermal action on the film until it darkens and bleaches, is demonstrated. Under CW near ultraviolet (NUV) laser action, the film was modified at a power density of 0.74 to 1.09 kW/cm². The near-infrared (NIR) laser pulses used ensured the film structure modification at a power density of 1.45 kW/cm² and a pulse duration of 4 to 20 ns. Scanning with a laser spot in these modes provides the desired change in the film’s optical characteristics, and this becomes a serious alternative to the technology of heat treatment in an oven.

Rare earth activated powders are widely regarded as promising candidates for optical thermometry due to their unique photoluminescence characteristics. The paper presents the structural and luminescent properties of crystalline powders of gadolinium and yttrium oxides (Gd_1−xY_x)₂O₃, doped with Nd³⁺ ions, synthesized by the liquid polymer-salt method. The addition of polyvinylpyrrolidone increases the homogeneity of the mixture and ensures high adhesion of the resulting powders. Scanning electron microscopy shows that powders are μm-sized aggregates, which consist of particles with several tens of nanometers in size. A smooth shift of the diffraction peaks of the powders occurs when Gd is replaced by Y without additional peaks. The successive decrease in the lattice constant of the powders from 10.816 to 10.607 Å confirms the existence of continuous solid solutions in the system. The Stark sublevels of the ⁴F_3/2 → ⁴I_9/2 fluorescent band are shifted to 4 nm when Gd is replaced by Y since the strength of the local field has a stronger effect on the inner F-shell of Nd ions in the case of Y. For thermometry, we chose the ratio of the fluorescence intensities between the Stark sublevels ⁴F_3/2(2) → ⁴I_9/2(2) and ⁴F_3/2(1) → ⁴I_9/2(2). The best obtained sensitivity is 0.22% °C⁻¹ for Nd-doped GdYO₃ powder in the range of 10–70 °C. This value of temperature sensitivity, together with radiation and excitation lying in the biological window, opens the possibility of using Nd³⁺-doped (Gd_1−xY_x)₂O₃ powders for real-time thermal probing of under tissue luminescence with sub-degree resolution.

The paper presents the results of a study into the physicochemical and spectral-luminescent properties of fluorophosphate glasses doped with thulium ions and a thulium/ytterbium pair. The DSC analysis performed showed that an increase in the concentration of rare earth ions leads to an increase in the crystallization stability of glasses. The measurement and analysis of luminescence spectra in the infrared region of the spectrum, as well as the study of energy transfer from ytterbium ions to thulium ions, showed that an increase in the concentration of thulium ions leads to efficient population of the upper laser level due to the cross-relaxation process. When glass is activated with a thulium/ytterbium pair, efficient energy transfer from ytterbium ions to thulium ions is observed at thulium fluoride concentrations above 0.5 mol %, which also leads to population of the upper laser level and an increase in the luminescence intensity in the wavelength range of 1700–1800 nm.

The effect of additives in sodium germanate glass on the up-conversion luminescence of an erbium ion was studied. Samples of glasses were prepared by high-temperature synthesis in corundum crucible. Synthesis temperature was 1250 °С. Synthesized glass had a composition of 58,95GeO2–27,79Na2O–8,67Yb2O3–4,34LaO–0,25Er2O3 mol% with additives of 5 mol% of the following oxides: Al2O3, Nb2O5, SiO2, BaO, TiO2, PbO, P2O5, MgO. Up-conversion luminescence spectra were recorded in the wavelength range from 450 to 700 nm when excited by a semiconductor laser at 975 nm. Three bands were identified on the luminescence spectra corresponding to radiative transitions of the erbium ion 2H11/2→4I15/2 with maximum of about 520 nm; 4S3/2→4I15/2 with maximum of 550 nm and 4F9/2→4I15/2 with maximum of 670 nm. The luminescent properties of the glass with additives were compared to those of the initial glass. The effect of additives on the relative intensity redistribution of upconversion luminescence was shown. Compared to the red luminescence band (4F9/2→4I15/2), the green band (2H11/2→4I15/2) intensity is a maximum for glass with the addition of phosphorus oxide; glass with the addition of lead oxide has the minimum intensity. The obtained dependence of the relative intensities of the up-conversion luminescence bands on the glass composition can find practical application in the development of optical luminescent sensors, as well as up-converters for solar cells.

The synthesis of gadolinium oxide nanopowders doped with neodymium (Gd₂O₃:Nd³⁺) 30nm in size was carried out using the citrate sol-gel method that included the simultaneous stabilization of nanoparticles using citric acid and polyvinylpyrrolidone (PVP). This study proposes and assesses a sol-gel synthesis process that involves the use of two different organic stabilizers with different thermal stabilities. Citric acid and polyvinylpyrrolidone were used as organic modifying components, playing a double role in the synthesis process, that is, acting as stabilizers of forming nanoparticles in colloidal solutions and serving as fuel additives in the process of heat treatment of materials. The structural and optical properties of Gd₂O₃:Nd³⁺ were investigated using photoluminescence, FTIR spectroscopy, DTA/TG, scanning electron microscope (SEM), and XRD analysis.