Ultrathin ohmic contacts were fabricated on GaP(111) single crystals using argon ion (Ar⁺) implantation at an energy of E₀ = 2 keV and a dose of D = 2 × 10¹⁷ cm⁻², under high vacuum conditions (10⁻⁷ Pa). Post-irradiation analysis revealed a significant enrichment of the surface with gallium, reaching a concentration of approximately 90 at.%. Subsequently, a nickel (Ni) film with a thickness of about 1000 Å was deposited onto the GaP(111) surface to form the contact. This metallization step led to a three- to fourfold reduction in the total thickness of the contact layer compared to conventional approaches. Upon thermal treatment at T = 850 K, the initially disordered GaP(111) layers recrystallized, resulting in a polycrystalline contact structure. After annealing, the thickness of the contact layer increased by approximately 1.5 times, reaching 400–450 Å, which is still around 2.5 times thinner than the characteristic thickness (dₙ) in the Ni/pure-GaP system. These findings demonstrate that ion implantation, followed by controlled metallization and annealing, provides an effective route for producing ultrathin, thermally stable ohmic contacts for GaP-based semiconductor devices.

The nanoporous structure of thermally modified carbon materials was studied using the small-angle X-ray scattering (SAXS) method. An analysis of scattering curves in Guinier and Porod coordinates was carried out for the initial and thermally activated materials at 400 °C for 30-240 minutes. It was established that thermal treatment for 150-180 minutes promotes the formation of a mesoporous structure with a radius of gyration ranging from 2.69 to 3.53 nm. The application of the Porod method made it possible to assess the fractal morphology of the surface, which varies from smooth to fractal. The obtained results indicate the possibility of controlled regulation of the porosity of carbon materials for sorption and electrochemical applications.

A study was conducted on the interaction of Zinc sulfide, obtained by the method of self-propagating high-temperature synthesis, and purified from oxygen with Europium (III) fluoride. The optical properties of the obtained systems were studied. The luminescence spectra show a decrease in its intensity for the samples after their heat treatment, which occurs due to the possible reaction with partial disappearance of Europium (III) fluoride. A hypothesis was proposed regarding the redox mechanism of interaction between the reagents with the formation of Europium (II) fluoride and other compounds.

The paper presents the results of the study of the crystal structure of six selenides of the composition R3Ag4kGe1.25-kSe7 (R – La, Ce; k = 0.05; 0.10; 0.15) as promising materials for use in various semiconductor technologies. Due to their potentially interesting nonlinear optical, magnetic and electrical properties, as well as other unique characteristics, these selenides can find application in scientific research and engineering developments, which opens up opportunities for the creation of modern materials with new functional properties. The crystal structure of the selenides La3Ag0.20Ge1.20Se7 (А) [a = 10.779(1) Å, c = 6.0876(8) Å, RI = 0.0982, RP = 0.2544], La3Ag0.40Ge1.15Se7 (B) [a = 10.7821(9) Å, c = 6.0927(7) Å, RI = 0.0950, RP = 0.2377], La3Ag0.60Ge1.10Se7 (C) [a = 10.7977(5) Å, c = 6.0997(5) Å, RI = 0.0920, RP = 0.2156], Ce3Ag0.20Ge1.20Se7 (D) [a = 10.6948(5) Å, c = 6.0635(6) Å, RI = 0.1130, RP = 0.2649], Ce3Ag0.40Ge1.15Se7 (E) [a = 10.7074(6) Å, c = 6.0697(7) Å, RI = 0.0977, RP = 0.2529] and Ce3Ag0.60Ge1.10Se7 (F) [a = 10.7147(4) Å, c = 6.0729(4) Å, RI = 0.0985, RP = 0.2100] was studied by powder X-ray diffraction. The structure is represented by various geometric units, trigonal prisms with two additional atoms [R 8Se], tetrahedra [Ge 4Se], and monohedra [M 3Se]. These structural elements indicate a complex structure of selenides, which includes various types of chemical bonds and interactions between atoms in the crystal lattice. The synthesized selenides crystallize in the hexagonal symmetry (La3CuSiS7 structure type; space group P63; Pearson symbol hP24,173). La or Ce atoms are localized in the 6c site (x y z), atoms of the statistical mixtures M(Ag + Ge) in the 2a site (0 0 z), and Ge atoms are in the 2b site (1/3 2/3 z). Selenium in the crystal lattice has three atomic sites, Se1 (2b site), Se2 and Se3 (6c site). The primitive hexagonal unit cell contains two La(Ce)3Ag4kGe1.25-kSe7 formula units. The trigonal prisms [R 8Se] are connected by edges and form “blocks” of three prisms in each. The [R(Ag + Ge) 6Se] octahedra have common faces and form “columns” in the direction of the main axis. Trigonal prisms and octahedra form common faces. The [Ge 4Se] tetrahedra are isolated from each other.

Tin doped SrCo2O4 thin films at 0%, 3% and 5% on "pyrex" glass substrates have been prepared by Sol-gel Dip-coating method. In both cases cobalt nitrate, strontium nitrate and tin chloride were used as cobalt and strontium precursor and tin dopant source, respectively. X-ray diffraction analysis confirms the SrCo2O4 spinel crystal structure (311) as the preferential orientation with crystallite sizes ranging from 23.58 to 25.44 nm. Analysis of optical transmission spectra as a function of wavelength shows that transmission of the doped films is found to be superior to the undoped film and the band gaps (Eg) decreased from 1.48 to 1.43 eV by Sn dopants. Complex impedance spectroscopy indicates that the grain boundary effect is dominant in the mechanism of conduction. The resistance at the room temperature varied from 47.75 Ω to 41.87 Ω for variation of Sn concentration.

The article analyzes the state of hydrocarbon production potential of Ukraine with a review of oil and gas hard-to-recover reserves. Ensuring reliable delineation of horizons needs the forming of cement stone with appropriate characteristics. The importance of forming a high-quality insulating screen for oil and gas wells is confirmed, both in terms of hydrocarbon production and in terms of labor safety and environmental impact. The main technological parameters of the plugging mud based on material DRCT and cement PCT I-100, as well as their physical-and-mechanical properties of cement stone, were determined. According to the results of the research, both in terms of the parameters of the plugging mud and the physical-and-mechanical properties of the cement stone, an advantage and improved values of indicators were obtained for the plugging material based on composite cement DRCT compared to cement PCT I-100. T It was found that the formed cement stone based on material DRCT has a densely packed structure. The permeability of cement stone samples based on DRCT in fresh and formation water storage was evaluated. The gas permeability for the researched samples is almost the same, which indicates the absence of a degrading effect on the cement stone. The obtained results indicate that the material DRCT is suitable for cementing oil and gas well casing. The results of the introduction of the plugging material based on DRCT during the cementing of casing string diameter 127 mm in well No. 105 of the Verkhnyomaslovetske field confirmed the success of its application.

The paper presents the results of studies of single-phase boride layer formation and solid-gas siliconization on carbon structural steel. The influence of powder grain size and composition of the saturating mixture on the structure and properties of diffusion coatings is shown. The properties of the obtained surface structures are compared with those of PVD-obtained chromium nitride coatings. The possibility of obtaining thick diffusion single-phase boride and silicide layers that are not inferior in mechanical and chemical characteristics to nitride layers obtained by ion-plasma deposition was established. The presence of 75,7% FeSi, 19,6% Si2CN4 та 4,8% Al5Fе phases in the silicide layer was shown, which provided high oxidation resistance at a temperature of 1000°C

Today's world has focused on investigating the thermoelectric properties of semiconductors related to problems such as direct conversion of heat energy to electrical energy and direct conversion of electrical energy to heat. In addition, the investigation of the thermoelectric properties of semiconductors is one of the basic researches of semiconductor physics and is important for the development of related sciences. Thermoelectric semiconductors are known to have the most usage area even now; It is thought that it can be used in different fields in the near future. Systems made of thermoelectric semiconductors are used in a wide area ranging from space technology to white goods technology. The research of these systems continues by deepening and expanding day by day. Because the basic information obtained here is transferred to the industry in a shorter time compared to other technologies and makes money. Therefore, most research has focused on the thermoelectric properties of semiconductors and thermoelectric technology. In the article, thermoelectric parameters of P- type Bi2Te3 semiconductors in the temperature range of 291-373K were investigated. The thermoemf, electrical conductivity, thermal conductivity, Z parameter behaviour at high temperatures of two types of P-type semiconductors obtained by two different methods were investigated and compared with the theoretical findings. In addition, using the variation of electrical conductivity with temperature, the band gap of the semiconductors was calculated separately and compared with the theory. It has been determined that the experimental results obtained are the same as the theoretical information within the error limits.

The thermodynamic stability and mixing behavior of the MoS₂-WS₂ system were investigated using a cluster expansion model constructed from density functional theory (DFT) calculations. The alloy cluster expansion approach enabled the efficient sampling of atomic configurations, overcoming the computational limitations of direct DFT calculations. The accuracy of the cluster expansion model was validated against additional DFT calculations, achieving a root-mean-squared error close to 1.0 × 10⁻⁴ eV/atom and R2 = 0.74. The mixing energy landscape was analyzed to determine the existence of ordered ground-state structures and assess the stability of solid solutions. The results indicate that MoS₂-WS₂ forms a stable solid solution across the full compositional range, with specific ordering tendencies at a broad range of intermediate atomic concentrations of tungsten, from XW = 0.33 to 0.66. The constructed convex hull suggests a multitude of ground states in this range with ordering patterns of a single solute atom residing in a hexagon of solvent atoms within a single layer. Generally small mixing energy values imply a dominant role of entropy at synthesis temperatures. The findings provide insight into the thermodynamic factors governing mixing in transition metal dichalcogenide MoS₂-WS₂ solid solutions, contributing to the rational design of materials based on them.

Досліджено дисперсію показника заломлення та область краю фундаментального поглинання в тонких плівках Ga1–xAlxN (x=0; 0,03; 0,07), отриманих методом високочастотного іонно-плазмового розпилення. Показано, що дисперсійна залежність отриманих плівок має складний вигляд. Встановлено, що величина оптичної ширини забороненої зони при зростанні концентрації Al від 0 до 7 мол.% зростає від 3,28 до 3,58 еВ. На основі встановлених прямо зонних дозволених фото переходів електронів в області краю фундаментального поглинання проведено оцінку величини зведеної ефективної маси вільних носіїв заряду та їхньої концентрації. Показано, що зсув краю фундаментального поглинання в тонких плівках Ga1–xAlxN (x=0; 0,03; 0,07) зумовлений ефектом Бурштейна-Мосса.