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 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 article presents the results of measuring the luminescence spectra, luminescence excitation spectra and luminescence spectra under high pressures for LaAlO₃:Pr with concentration of 1%. The materials were synthesized by solid phase synthesis. Diffraction pattern is fully relates to LaAlO₃ phase. The photoluminescence spectra show the main energy transitions. The change in the position of the main bands under the hydrostatic pressure of 23, 55, 160 and 191 kBar was demonstrated. The main band at 491 nm is slightly red-shifted, while the line at 605 nm is shifted to the high-energy part of the spectrum. The intensity of all bands increases with increasing hydrostatic pressure. The dynamics of changes in the intensities of maxima and emissions from different transitions are analyzed. Studies of luminescence under high hydrostatic compression are important in observing changes in the internal structure and electronic states of materials under the influence of high pressure, studying internal processes such as recombination of electrons and holes, transitions between energy levels and the release of photons. Understanding the changes that occur under compression can help researchers develop new materials with unique properties.