The technological procedure of the manufacturing of the LiNbO3' single crystals doped with 5 mol.% MgO is described in this paper. The results of the investigation of the crystal optical properties, ESR spectra and optical homogeneity are presented. The refractive index dispersion in 300-700 nm region and their temperature dependencies in 20-500 "C range are measured.The dispersion curve is approximated by the two oscillator Sellmeier formula. The data on the LiNbO3 : MgO crystal optical resistance are presented.

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Luminescence spectral and kinetic characteristics of CsPbCl3 nanocrystals, dispersed in perovskite-like CsSrCl3 matrix, have been studied under excitation by synchrotron radiation in the UV–visible spectral region (4 to 20 eV). Various time components in the decay kinetics of CsPbCl3 nanocrystals appear due to direct excitation of nanocrystals or reabsorption of the luminescence of other emitting centres. Shortening of the luminescence decay time of the CsPbCl3 nanocrystals with respect to that observed for a CsPbCl3 single crystal has been explained as evidence of quantum-size effect.

We have studied spectral and temperature variations of the principal refractive indices of lithium potassium sulfate crystals, LiKSO 4, subjected to uniaxial mechanical pressures. Notable baric increases in the refractive indices are found, which have been interpreted using classical single-oscillator dispersion Sellmeier equation and Lorentz–Lorenz formula. Significant pressure-induced shifts of low-temperature phase transitions in LiKSO 4 are revealed and qualitatively explained in terms of modifications of crystalline structure imposed by the pressures. It is established that high enough pressures applied along the crystallographic axis c can generate a "triple point" on the phase diagram "temperature-uniaxial pressure". It is inferred that the temperature behavior of the refractive indices below the room temperature cannot be interpreted as a pure result of spontaneous strains and should possibly involve some other mechanisms, e.g., a hypothesis of incommensurately modulated phase existing about below 255 K.