This paper presents the results of investigations into the optical properties of LiF crystals doped with oxides of different metals (Li, W, Ti, Fe). It has been proved that, during the growth of...

The present paper focused on the study of spectral–kinetic characteristics of luminescence in two batches of yttrium aluminum garnet (YAG):Ce-based phosphors synthesized in different years by two manufacturers: NPO “Platan” in Russia and “GrandLux” in the People’s Republic of China (PRC). Upon studying the structural characteristics of the phosphors—elemental composition, morphology, and X-ray diffraction (XRD) patterns—it was concluded that both types of YAG:Ce phosphors are highly imperfect. The presence of heterogeneities of different nature was accompanied by the introduction—to compensate for charges and elastic stresses—of intrinsic lattice defects during synthesis. There is a high probability of creating complex defects during phosphor synthesis. Luminescence properties (full width at half maximum (FWHM), spectral position of the emission peaks, excitation spectra of emission, emission decay time) are affected by the nearest environment of the luminescence center; whereas the degree of correlation of defects (distance between the components of the donor–acceptor pair) does not depend on the concentration of impurities, intrinsic defects, and their ratio. The results do not fit into the framework of existing ideas regarding the processes in phosphors as systems with widely distributed luminescence centers. The patterns obtained in the paper are discussed based on a hypothesis according to which a nanodefect phosphorus crystal phase is formed during the synthesis.

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, Y₃Al_xGa_(5-x) O₁₂, MgAl₂O₄, ZnAl₂O₄, MgWO₄, ZnWO₄, Ba_xMg_(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.

Synthesis in the radiation field is a promising direction for the development of materials transformation processes, especially those differing in melting temperature. It has been established that the synthesis of yttrium–aluminum ceramics from yttrium oxides and aluminum metals in the region of a powerful high-energy electron flux is realized in 1 s, without any manifestations that facilitate synthesis, with high productivity. It is assumed that the high rate and efficiency of synthesis are due to processes that are realized with the formation of radicals, short-lived defects formed during the decay of electronic excitations. This article presents descriptions of the energy-transferring processes of an electron stream with energies of 1.4, 2.0, and 2.5 MeV to the initial radiation (mixture) for the production of YAG:Ce ceramics. YAG:Ce (Y₃Al₅O₁₂:Ce) ceramics samples in the field of electron flux of different energies and power densities were synthesized. The results of a study of the dependence of the morphology, crystal structure, and luminescence properties of the resulting ceramics on the synthesis modes, electron energy, and electron flux power are presented.

We have studied the spectral and kinetic characteristics of activated photo- and cathodoluminescence of LiF-O and LiF-WO₃ crystals in the spectral range of 3.6–1.6 eV using methods of pulsed spectrometry with nanosecond time resolution in the temperature range of 15–300 K and in the range of ionizing radiation dose absorbed by crystals of 10²−2 × 10³ Gy.