Igor Mikhaylovich Pritula

Ternary chalcogenide semiconductors are of significant interest for photovoltaic and optoelectronic applications due to their tunable optical properties and structural flexibility. Among these, ZnIn2Se4 stands out as a promising, non-toxic light-harvesting absorber material for buffer layers in heterojunction solar cells. This study reports on the high-temperature, solid-state synthesis of ZnIn2Se4 and examines the effects of temperature and annealing (homogenization) duration on its structural, morphological, and optical properties. The material was annealed at temperatures between 800°C and 970°C for 3, 5, or 10 days. The resulting powders were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis diffuse reflectance spectroscopy. XRD analysis revealed that the resulting powders were an inhomogeneous mixture of the main ZnIn2Se4 phase, the Zn1.5In3Se6 defective chalcopyrite phase, the initial residual precursor phase ZnSe, and two-component phases In2Se3 and In3Se4. Increasing the annealing temperature and homogenization duration yielded a ZnIn2Se4 single-phase chalcopyrite structure with high crystallinity. The optical band gap (Eg) shows a nonlinear dependence on the amount of defective phase (Zn1.5In3Se6) present. The minimum band gap of 1.24 eV was observed in the sample that was annealed at 800 °C for 5 days. DFT-based electronic structure calculations revealed that the Zn1.5In3Se6 defective phase is not stable under normal conditions, but it exists within the ZnIn2Se4 phase in the form of microinclusions. This symbiosis of the two phases is accompanied by the formation of two additional phases: In2Se3 and In4Se3.

Experimental results of growth of (Cr, Co, Fe)-co-doped ZnSe crystals, for laser applications in the range 2–5 µm, by the vertical Bridgman method under high argon pressure are described for the first time. A comparative study involving crystallographic analysis, X-ray diffraction, scanning electron microscopy, infrared spectroscopy, and other physical characterization techniques is carried out for co-doped (Cr, Co, Fe):ZnSe crystals. Growth features, morphology and optical properties of the crystals are studied and correlated with their crystal structure. The feasibility of producing large, homogeneous optical crystals with a controlled and uniform distribution of multiple activators throughout the crystal volume is also demonstrated.

In this study, binary ZnSe:Fe²⁺ crystals and a concentration series of ternary Zn _1-x Mg _x Se:Fe²⁺ (0 < x < 0.6) were grown using the vertical Bridgman method in graphite crucibles under high argon pressure. The influence of Mg incorporation on the structural perfection, electronic energy levels, and optical absorption/emission characteristics was systematically investigated. With increasing Mg content, a monotonic redshift of both absorption and luminescence bands was observed, which is attributed to modifications in the crystal field surrounding Fe²⁺ ions and to changes in the host lattice parameters. The correlation between composition, crystal structure, and optical response was analyzed to elucidate the mechanisms of Fe²⁺-related transitions. These results demonstrate the potential of Zn _1-x Mg _x Se:Fe²⁺ as tunable mid-infrared laser media and provide guidelines for the compositional engineering of A²B⁶-based laser materials.

The design and manufacturing technology of interference-absorbing short-wave filters based on a layered composition of Si–SiO on a sapphire substrate of various shapes was developed. A transition layer of SiO was applied to the surface of the substrate, alternating with layers of Si–SiO with an odd number of quarter-wave layers of materials with high (Si) and low refractive indices (SiO), and the application of an outer layer of SiO as an appropriate control of the materials’ thickness. The optical properties of the infrared light filter were studied. It was established that the created design of the light filter provides the minimum light transmission in the visible region of the spectrum from 0.38 to 0.78 µm and the maximum in the near infrared region from 1.25 to 5 µm and has stable optical indicators. A method for studying the stress–strain state and strength of a multilayer coating of a light filter under the action of a local arbitrarily oriented load was developed. For simplicity in the analysis and for obtaining results in the analytical form, the one-dimensional model of the configuration “multilayer covering—firm substrate” constructed earlier by authors was used. From a mechanical point of view, the upper protective layer of the multilayer coating was modeled by a flexible plate, and the inner operational composite N-layer was subjected to Winkler’s hypothesis about the proportionality of stresses and elastic displacements.

Conoscopic interference patterns, channelled spectra and polarimetric techniques have been used for the characterization of pure and doped (with L-arginine amino acid) potassium dihydrogen phosphate (KDP) single crystals. Experimental polarimetric data have been obtained for the frequently used wavelength of 633 nm and for two close wavelengths of 532 and 543 nm in a high-accuracy dual-wavelength polarimeter. The measurement of eigenwave ellipticity in the [100] and [010] directions and between 295 and 340 K shows small differences in the absolute values of the specific optical rotations of KDP crystals doped with L-arginine in the range of 0.7–3.8 wt%. It is found that the gyration tensor component g ₁₁, specific optical rotation and eigenwave ellipticity show different dispersion in the visible spectral region.

The threshold of the magnetic effect on the microhardness of potassium dihydrogen phosphate (KDP) crystals has been found. It was previously shown that the preliminary exposure of such crystals to a...

The spectroscopic and laser characteristics of two benzopyrane derivatives for 600–670 nm spectrum region of lasing in preliminarily annealed silica xerogel matrices in non-selective cavity under laser pumping at 551 nm have been measured and analysed. The influence of molecular structure of the dyes on their non-radiating losses has been revealed. The specific output laser energy of the studied matrices was approximately equal to the ones for corresponding methanol solutions under the same pumping conditions. The laser spectra of the matrices were displaced to the red region from the fluorescence maximum by about 1000–1500 cm⁻¹ in a nonselective cavity. Such spectral displacement may improve the characteristics of biosensors made on the basis of these matrices because it shifts their emission spectrum to the range of deeper penetration into biological tissues.