Search

This paper presents the results of ceramic synthesis in the field of a powerful flux of high-energy electrons on powder mixtures. The synthesis is carried out via the direct exposure of the radiation flux to a mixture with high speed (up to 10 g/s) and efficiency without the use of any methods or means for stimulation. These synthesis qualities provide the opportunity to optimize compositions and conditions in a short time while maintaining the purity of the ceramics. The possibility of synthesizing ceramics from powders of metal oxides and fluorides (MgF2, BaF2, WO3, Ga2O3, Al2O3, Y2O3, ZrO2, MgO) and complex compounds from their stoichiometric mixtures (Y3Al3O12, Y3AlxGa(5−x) O12, MgAl2O4, ZnAl2O4, MgWO4, ZnWO4, BaxMg(2−x) F4), including activators, is demonstrated. The ceramics synthesized in the field of high-energy electron flux have a structure and luminescence properties similar to those obtained by other methods, such as thermal methods. The results of studying the processes of energy transfer of the electron beam mixture, quantitative assessments of the distribution of absorbed energy, and the dissipation of this energy are presented. The optimal conditions for beam treatment of the mixture during synthesis are determined. It is shown that the efficiency of radiation synthesis of ceramics depends on the particle dispersion of the initial powders. Powders with particle sizes of 1–10 µm, uniform for the synthesis of ceramics of complex compositions, are optimal. A hypothesis is put forward that ionization processes, resulting in the radiolysis of particles and the exchange of elements in the ion–electron plasma, dominate in the formation of new structural phases during radiation synthesis. [ABSTRACT FROM AUTHOR]

TeO2-BaF2-Er2O3-Dy2O3 laser glasses were prepared using the melt-quenching method. The bound water that can capture the excited state energy was reduced by physical and chemical methods. We did not observe a significant Er3+ emission peak at 2.7 μm in fluorescence spectra, which may be due to the efficient energy transfer process (ET2). Meanwhile, we found a broadband gain span of approximately 400 nm in fluorescence spectra at the 2.85 μm band, attributed to the 'vector summation' of the energy level radiation transition and the change of the glass network. Subsequently, we explored the structural properties of the glass. The results indicated that the Gaussian peak located at 250 cm−1 drifts toward 370 cm−1, which may be caused by the fracture or recombination of Te-O-Te and a decrease in the bridge oxygen content with the increasing concentration of Er2O3. The topology cage structure around the luminescence center of rare earth ions is changed and the stability of the optically active center is enhanced, finally contributing to the enhancement of luminescence. Meanwhile, the maximum σemi and gain coefficient of Dy3+ reach up to 7.22 × 10−21 cm2 and 7.37 cm−1, respectively. The comprehensive results show that the fluorotellurite glass designed in this study is expected to be a gain medium for mid-infrared lasers in remote sensing monitoring, military, and other fields. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of multicolor light-emitting nanomaterials based on rare earths (RE3+) are of great importance due to their possible use in optoelectronic devices, such as LEDs or displays. In the present work, oxyfluoride glass-ceramics containing BaF2 nanocrystals co-doped with Tb3+, Eu3+ ions were fabricated from amorphous xerogels at 350 °C. The analysis of the thermal behavior of fabricated xerogels was performed using TG/DSC measurements (thermogravimetry (TG), differential scanning calorimetry (DSC)). The crystallization of BaF2 phase at the nanoscale was confirmed by X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM), and the changes in silicate sol–gel host were determined by attenuated total reflectance infrared (ATR-IR) spectroscopy. The luminescent characterization of prepared sol–gel materials was carried out by excitation and emission spectra along with decay analysis from the 5D4 level of Tb3+. As a result, the visible light according to the electronic transitions of Tb3+ (5D4 → 7FJ (J = 6–3)) and Eu3+ (5D0 → 7FJ (J = 0–4)) was recorded. It was also observed that co-doping with Eu3+ caused the shortening in decay times of the 5D4 state from 1.11 ms to 0.88 ms (for xerogels) and from 6.56 ms to 4.06 ms (for glass-ceramics). Thus, based on lifetime values, the Tb3+/Eu3+ energy transfer (ET) efficiencies were estimated to be almost 21% for xerogels and 38% for nano-glass-ceramics. Therefore, such materials could be successfully predisposed for laser technologies, spectral converters, and three-dimensional displays. [ABSTRACT FROM AUTHOR]