A. K. Zhubaev

To identify the regularities of formation of a thermally stable system “Iron-based solid solution— intermetallic compound”, it is necessary first to find out the conditions for obtaining a solid solution. The spectra of ⁵⁷Fe nuclei in Iron-based solid solutions were modeled. A comparison of the calculated spectra with the experimental spectra of the layered system Al_25%Be_75%(2 µm)–Fe(10 µm) synthesized by ion-plasma deposition of Aluminum and Beryllium on an armco-Iron substrate and subjected to thermal annealing allows us to conclude that a solid solution of α-Fe(Al,Be) was formed at 650°C.

The determination of the phase formation mechanism in two-layer Sn–Fe systems will make it possible to establish the possibility of creating thermally stable layered systems. Studies of thermally induced phase transformations in the layered system Sn(4 µm)–Fe(10 µm) were carried out. The formation of a solid solution of α-Fe(Sn) and intermetallic compounds was revealed. The spectra of ⁵⁷Fe nuclei in intermetallides of the Fe–Sn binary system were modeled. Comparison of the model and experimental Mossbauer spectra makes it possible to identify the intermetallides FeSn and Fe₃Sn₂. The possibility of creating a thermally stable spatially inhomogeneous Fe₃Sn₂–α-Fe(Sn) system is shown.

In order to identify the regularities of thermally induced phase formation, the studies of layered system of Fe(2 µm)–Fe(10 µm) obtained by ion-plasma sputtering and subjected to thermal annealings at 720°C have been carried out by means of Mossbauer spectroscopy. The formation of a solid solution of α‑Fe(Be) was revealed. The Mossbauer spectra of a solid solution Fe–(0.5–10%)Be of Beryllium atoms in Iron are modeled. Comparison with experimental spectra shows a good correlation.

The article presents the results of measuring the luminescence spectra and luminescence excitation spectra for YAG:Eu with europium concentrations of 2, 6, 8, and 10%. The materials were synthesized by solid-phase synthesis. For samples with europium concentrations of 2, 8, and 10%, the diffraction patterns showed full agreement with the phases. However, the yttrium–aluminum–perovskite phase was present in the sample with a concentration of 6%, even though the samples were obtained under the same conditions. The spectra of the photoluminescence excitation and photoluminescence were recorded for all samples. The concentration dependences of the luminescence bands and luminescence excitation bands were also plotted. The bandgap and absorption spectra were simulated for the sample of YAG:Eu, doped with 2–4 ions of europium for comparison.

The results from simulation of the structural and optical properties of YAG pure, doped with two ions and four ions of lanthanum, are presented in this paper to investigate the effect of dopants on a crystal. The simulation was carried out in the Quantum Espresso program. The band structure, density of states, the dielectric function, absorption, refractive index, energy loss function and reflectivity were calculated for different samples. It can be assumed that with a rise in concentration density of states, the impurity atom increases and the position of the most populated levels shifts to the right in the region of negative energies in the case of two atoms and to the left in the case of four atoms of lanthanum. We can draw conclusions about the transparency of the sample in the visible region, because the absorption spectra appear in the UV region. This transparent nature makes them perfect candidates for deep UV nonlinear optical materials. From the analysis of dielectric function, it is clear that in the case of YAG doped with two ions of lanthanum, two peaks appeared compared to the sample with one peak in pure and doped with four ions. Anisotropy is most pronounced with an increase in the degree of doping.

The layered Zr(2 μm)-Fe(10 μm), Sn(4 μm)-Fe(10 μm) and Sn(4 μm)-Zr(2 μm)-Fe(10 μm) systems subjected to isochronous annealings have been studied. The sequence of phase transformations is determined. In the three-layer system, the formation of intermetallic compounds with a high content of Zirconium and a solid solution α-Fe(Sn, Zr) is established. The spectra of ⁵⁷Fe nuclei in Iron-based alloys of various concentrations were calculated. A comparison with the experimental spectra of the layered systems obtained by ion-plasma deposition of Tin and Zirconium on an armco iron substrate and subjected to thermal annealing at 750 °C showed a good correlation.