East European Journal of Physics https://periodicals.karazin.ua/eejp <p>EEJP is an international peer-reviewed Journal devoted to experimental and theoretical research on the nuclear physics, cosmic rays and particles, high-energy physics, solid state physics, plasma physics and controlled thermonuclear fusion, physics of charged particle beams, plasma electronics, radiation materials science, physics of thin films, condensed matter physics, functional materials and coatings, technical thermophysics and industrial power,&nbsp;medical physics and physical technologies in an interdisciplinary context.</p> <p>EEJP registered by the order of Ministry of Education and Science of Ukraine <strong>No. 1643 of 28.12.2019</strong>, and included in the list of scientific professional Editions of Ukraine (<strong>category “A”, specialty: 104, 105</strong>), in which results of dissertations for obtaining Ph.D. and Dr. Sci. degrees in physical and mathematical sciences can be published.</p> <p>The Journal is a part of the <strong>Web of Science Core Collection (ESCI)&nbsp;</strong>scientometric platform and indexed by&nbsp;<strong>SCOPUS</strong>.</p> <p>&nbsp;</p> en-US <p>Authors who publish with this journal agree to the following terms:<br><br></p> <ol type="a"> <ul> <li class="show">Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a&nbsp;<a href="http://creativecommons.org/licenses/by/4.0/" target="_new">Creative Commons Attribution License</a>&nbsp;that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.</li> </ul> </ol> <ol type="a"> <ul> <li class="show">Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.</li> </ul> </ol> <ol type="a"> <ul> <li class="show">Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See&nbsp;<a href="http://opcit.eprints.org/oacitation-biblio.html" target="_new">The Effect of Open Access</a>).</li> </ul> </ol> serhii.hirnyk@karazin.ua (Serhii Hirnyk) serhii.hirnyk@karazin.ua (Serhii Hirnyk) Tue, 28 Sep 2021 18:01:07 +0000 OJS http://blogs.law.harvard.edu/tech/rss 60 A Review on Processing Routes, Properties, Applications, and Challenges of Titanium Metal Matrix Composite https://periodicals.karazin.ua/eejp/article/view/17742 <p>Titanium is currently familiar for its light weight, high strength, and non-reactive nature over all the metals. Titanium metal matrix composites (TMCs) are very popular in the field of aerospace, automotive, defense, and biomedical because of their high specific strength, light weight, and biocompatibility nature. Some of the extensively used fabrication methods like powder metallurgy (PM), additive manufacturing (AM), and spark plasma sintering (SPS) have been reviewed here with some of the properties of TMCs.&nbsp;By varying various types of reinforcements, it is possible to achieve the required properties as per industrial and modern applications in TMC. This study also includes the consequence of sintering temperature on properties of TMCs like physical, mechanical, and structural. Titanium alloys are showing good mechanical and biomedical properties when reinforced with carbon fibers, borides, ceramics, and plenty of other materials as continuous fiber or discontinuous particulates and whiskers. In this paper, the&nbsp;applications of TMCs in aerospace, automobile, biomedical, and defense have been narrated.&nbsp;Besides all these favorable properties and applications, TMCs can’t be used extensively in the said applications because of their high cost and difficulty in machining, that discussed in this paper over various challenges of TMCs. The cost reduction can be done by making Ti - super alloys. In addition, there is a necessity for an effective cooling system during the machining of TMCs to enhance machinability and some of the effective methods which may enhance the machinability of TMCs were also discussed.</p> Hrudayanjali Pathi, Tapan Kumar Mishri, Sasmita Rani Panigrahi, Bijayalaxmi Kuanar, Biswajit Dalai Copyright (c) 2021 Hrudayanjali Pathi, Tapan Kumar Mishri, Sasmita Rani Panigrahi, Bijayalaxmi Kuanar, Biswajit Dalai https://periodicals.karazin.ua/eejp/article/view/17742 Tue, 28 Sep 2021 00:00:00 +0000 Nonlinear Cone Model for Investigation of Runaway Electron Synchrotron Radiation Spot Shape https://periodicals.karazin.ua/eejp/article/view/17743 <p>The runaway electron event is the fundamental physical phenomenon and tokamak is the most advanced conception of the plasma magnetic confinement. The energy of disruption generated runaway electrons can reach as high as tens of mega-electron-volt and they can cause a catastrophic damage of plasma-facing-component surfaces in large tokamaks and International Thermonuclear Experimental Reactor (ITER). Due to its importance, this phenomenon is being actively studied both theoretically and experimentally in leading thermonuclear fusion centers. Thus, effective monitoring of the runaway electrons is an important task. The synchrotron radiation diagnostic allows direct observation of such runaway electrons and an analysis of their parameters and promotes the safety operation of present-day large tokamaks and future ITER. In 1990 such diagnostic had demonstrated its effectiveness on the TEXTOR (Tokamak Experiment for Technology Oriented Research, Germany) tokamak for investigation of runaway electrons beam size, position, number, and maximum energy. Now this diagnostic is installed practically on all the present-day’s tokamaks. The parameter v<sub>┴</sub>/|v<sub>||</sub>|&nbsp;strongly influences on the runaway electron synchrotron radiation behavior (v<sub>||</sub> is the longitudinal velocity, v<sub>┴</sub> is the transverse velocity with respect to the magnetic field <em><strong>B</strong></em>). The paper is devoted to the theoretical investigation of runaway electron synchrotron radiation spot shape when this parameter is not small that corresponds to present-day tokamak experiments. The features of the relativistic electron motion in a tokamak are taken into account. The influence of the detector position on runaway electron synchrotron radiation data is discussed. Analysis carried out in the frame of the nonlinear cone model. In this model, the ultrarelativistic electrons emit radiation in the direction of their velocity v<sup>→</sup> and the velocity vector runs along the surface of a cone whose axis is parallel to the magnetic field <em><strong>B</strong></em>. The case of the small parameter v<sub>┴</sub>/|v<sub>||</sub>| (v<sub>┴</sub>/|v<sub>||</sub>|&lt;&lt;1, linear cone model) was considered in the paper: <em>Plasma Phys. Rep. </em><strong>22</strong>, 535 (1996) and these theoretical results are used for experimental data analysis.</p> Igor M. Pankratov, Volodymyr Y. Bochko Copyright (c) 2021 Igor M. Pankratova, Volodymyr Y. Bochko https://periodicals.karazin.ua/eejp/article/view/17743 Tue, 28 Sep 2021 00:00:00 +0000 Enhancing the Diffusion in Underdamped Space-Periodic Systems by Applying External Low-Frequency Fields https://periodicals.karazin.ua/eejp/article/view/17744 <p>This paper is devoted to the studies of the opportunities for the intensification of the particle diffusion in the periodic structures, for example, the crystals that are exposed to the action of the time-periodic fields of a different nature. These can be acoustic or electromagnetic fields. The trivial one-dimensional model of the motion of the particles in the potential lattice field under the thermal equilibrium has been used. The paper studies the interaction of rectangular fields with the frequencies less than 0.01 ω<sub>0</sub>, where ω<sub>0</sub> &nbsp;is the frequency of natural small vibrations of the particles in the systems with the low dissipation. The selected friction coefficient in dimensionless units is equal to γ'=0.03. The amplitude dependence of the intensification of the diffusion <em>D</em> under the action of the fields of a different frequency has been studied. It was shown that the diffusion coefficient can be increased by several orders of magnitude by applying the field of an appropriate amplitude and frequency. A maximum diffusion intensification is attained at ω→0. A maximum attained value of the diffusion coefficient at the periodic force corresponds to the case of the action of the constant force. However, at low frequencies a maximum intensification is only possible in the narrow range of field amplitudes F'oc&nbsp;γ'. A further increase in the field amplitude results in a decrease of the diffusion coefficient and it attains the value of the coefficient of the particle diffusion in the viscous medium <em>D<sub>vis</sub>=k'T'/γ'</em>, where <em>k'</em> &nbsp;is the Boltzmann coefficient and <em>T'</em> is the temperature. An increase in the frequency of the external force results in the extension of the range of forces at which <em>D&gt;D<sub>vis</sub></em>, however the value of the diffusion intensification is decreased. It was shown that the exceed of a certain threshold value of the amplitude of the external field&nbsp; results in the gain of the diffusion coefficient at least by the value of <em>η</em>=(<em>k'T'</em>e<sup>ε/<em>k'T'</em></sup>)/(<em>γ"D<sub>0</sub></em>, where ε&nbsp;is the value of the energy barrier during the passage of the particle from one cell of the one-dimensional lattice to another.&nbsp;The obtained data open prospects for the development of new technologies to exercise control over diffusion processes. It is of great importance for the production of nanomaterials with the specified structure, creation of the surface nanostructures, etc.</p> Ivan G. Мarchenko, Viktoriia Yu. Аksenova, Igor I. Marchenko Copyright (c) 2021 Ivan G. Мarchenko, Viktoriia Yu. Аksenova, Igor I. Marchenko https://periodicals.karazin.ua/eejp/article/view/17744 Tue, 28 Sep 2021 00:00:00 +0000 Sputtering of Oxides from LaNi5 Surface https://periodicals.karazin.ua/eejp/article/view/17745 <p>The changes in chemical composition of the intermetallic alloy LaNi<sub>5</sub> surface monolayers were studied using secondary ion mass spectrometry (SIMS) in the process of the alloy interaction with oxygen. The investigated samples were pellets made by pressing the fine-grained LaNi<sub>5</sub> alloy. Ar<sup>+</sup> ions having energies of 10-18&nbsp;keV were used as primary ions. The primary beam current density was 9-17&nbsp;μA·cm<sup>-2</sup>, which corresponds to the dynamic SIMS mode. The emission intensities of secondary ions were measured within the dynamic range of at least 6 orders of magnitude. Before the measurements, the samples were annealed in residual vacuum at a temperature of ~ 1000 K. After the annealing, the sample surface was cleaned using the primary ion beam until the mass-spectrum composition and secondary ion emission intensity stabilized completely. The gas phase composition was monitored using a gas mass spectrometer. The conducted studies showed that a complex chemical structure including oxygen, lanthanum, and nickel is formed on the surface and in the near-surface region of LaNi<sub>5</sub> as a result of its exposure to oxygen. Oxygen forms strong chemical bonds in such a structure with both components of the alloy. This is evidenced by the presence of a large set of oxygen containing emissions of positive and negative secondary ions with lanthanum, with nickel, and oxygen containing lanthanum-nickel cluster secondary ions in mass spectra. The resulting oxide compounds have a bulk structure and occupy dozens of monolayers. In such a bulk oxide structure, the outer monolayers are characterized by the highest ratio of oxygen atom number to the number of matrix atoms. This ratio decreases along the transition from the surface to the underlying monolayers. This process occurs uniformly, without any phase transformation. The observed secondary ions are not a product of association between sputtered surface fragments and oxygen in the gas phase at the fly-off stage after sputter-ejection, but they are products of the oxide compounds being sputtered, hence they characterize the composition of surface and near-surface region.</p> Viktor O. Litvinov, Ivan I. Okseniuk, Dmitriy I. Shevchenko, Valentin V. Bobkov Copyright (c) 2021 Viktor А. Litvinov, Ivan I. Okseniuk, Dmitriy I. Shevchenko, Valentin V. Bobkov http://creativecommons.org/licenses/by/4.0 https://periodicals.karazin.ua/eejp/article/view/17745 Tue, 28 Sep 2021 00:00:00 +0000 Tensoelectrical Properties of Electron-Irradiated N-Si Single Crystals https://periodicals.karazin.ua/eejp/article/view/17746 <p>Tensoresistance at uniaxial pressure for electron-irradiated n-Si single crystals at room temperature has been studied. Silicon single crystals for research were doped with phosphorus, concentration N<sub>d</sub>=2.2·10<sup>16</sup> cm<sup>-3</sup>, and irradiated by the electron flows of 5·10<sup>16</sup>&nbsp;el./cm<sup>2</sup>, 1·10<sup>17</sup> el./cm<sup>2</sup> and 2·10<sup>17</sup> el./cm<sup>2</sup> with the energy of 12 MeV. Measurements of tensoresistance and Hall constant were performed for the uniaxially deformed n-Si single crystals along the crystallographic directions [100] and [111]. Mechanisms of tensoresistance for the investigated n-Si single crystals were established based on the measurements of the tenso-Hall effect and infrared Fourier spectroscopy. It is shown that the tensoresistance of such single crystals is determined only by changes in the electron mobility under the deformation. In this case, the electron concentration will not change under the action of uniaxial pressure, because the deep levels of radiation defects belonging to the VO<sub>i</sub> VO<sub>i</sub>P complexes will be completely ionized. Ionization of the deep level of E<sub>V</sub>+0.35 eV, which belongs to the defect of C<sub>i</sub>O<sub>i</sub>, under the deformation will not be manifested and will not be affect on the tensoresistance of n-Si. It is established that the anisotropy of electron scattering on the created radiation defects, which occurs at the uniaxial pressure along the crystallographic direction [100], is the cause of different values of the magnitude of tensoresistance of n‑Si single crystals, irradiated by different electron flows. For the case of tensoresistance of the uniaxially deformed n-Si single crystals along the crystallographic direction [111], the dependence of its magnitude on the electron irradiation flow is associated with changes in the screening radius due to an increase in the effective electron mass. For the first time obtained at room temperature the increase of the magnitude of tensoresistance for the n-Si single crystals due to their irradiation by the electron flows of&nbsp;Ω&nbsp;≥1·10<sup>1</sup><sup>7</sup>&nbsp;el./cm<sup>2</sup> can be used in designing high uniaxial pressure sensors based on such n-Si single crystals with the higher value of tensosensitivity coefficient regarding available analogues. Such sensors will have increased radiation resistance and a wide scope of operation.</p> Sergiy Luniov, Petro Nazarchuk, Volodymyr Maslyuk Copyright (c) 2021 Sergiy Luniov, Petro Nazarchuk, Volodymyr Maslyuk https://periodicals.karazin.ua/eejp/article/view/17746 Tue, 28 Sep 2021 00:00:00 +0000 Structure and Physical Properties of Cast and Splat-Quenched CoCr0.8Cu0.64FeNi High Entropy Alloy https://periodicals.karazin.ua/eejp/article/view/17747 <p>The article investigates the structure and physical properties of the multicomponent high-entropy alloy CoCr<sub>0.8</sub>Cu<sub>0.64</sub>FeNi&nbsp; in the cast and quenched state. The composition of the alloy under study is analyzed using the criteria available in the literature for predicting the phase composition of high-entropy alloys. These parameters are based on calculations of the entropy and enthalpy of mixing and also include the concentration of valence electrons, the thermodynamic parameter Ω, which takes into account the melting point, entropy of mixing, and enthalpy of mixing. Another important parameter is the difference in atomic radii between the alloy components δ. Cast samples of the CoCr<sub>0.8</sub>Cu<sub>0.64</sub>FeNi alloy of nominal composition were prepared on a Tamman high-temperature electric furnace in an argon flow using a copper mold. The weight loss during the manufacture of ingots did not exceed 1%, and the average cooling rate was ~ 10<sup>2</sup>K/s. Thereafter, the cast ingot was remelted, and films were obtained from the melt. The splat quenching technique used in this work consisted of the rapid cooling of melt droplets when they collide with the inner surface of a rapidly rotating (~ 8000 rpm) hollow copper cylinder. The cooling rate, estimated from the film thickness, was ~ 10<sup>6</sup> K / s. X-ray structural analysis was performed on a DRON-2.0 diffractometer with monochromatic Cu K<sub>α</sub> radiation. Diffraction patterns were processed using the QualX2 program. The magnetic properties of the samples were measured using a vibrating sample magnetometer at room temperature. The microhardness was measured on a PMT-3 device at a load of 50 g. In accordance with theoretical predictions confirmed by the results of X-ray diffraction studies, the structure of the alloy, both in the cast and in the quenched state, is a simple solid solution of the FCC type. The lattice parameters in the cast and liquid-quenched states are 0.3593 nm and 0.3589 nm, respectively. Measurements of the magnetic properties showed that the CoCr<sub>0.8</sub>Cu<sub>0.64</sub>FeNi&nbsp; alloy can be classified as soft magnetic materials. In this case, quenching from a liquid state increases the coercivity. On quenched samples, increased microhardness values were also obtained. This can be explained by internal stresses arising during hardening.</p> Oleksandr I. Kushnerov, Valerii F. Bashev Copyright (c) 2021 Oleksandr I. Kushnerov, Valerii F. Bashev https://periodicals.karazin.ua/eejp/article/view/17747 Tue, 28 Sep 2021 00:00:00 +0000 Peculiarities in the Structure Formation and Corrosion of Quasicrystalline Al65Co20Cu15 Alloy in Neutral and Acidic Media https://periodicals.karazin.ua/eejp/article/view/17748 <p>In the present study, the structure and corrosion properties of quasicrystalline conventionally solidified Al<sub>65</sub>Co<sub>20</sub>Cu<sub>15</sub> alloy cooled at 5&nbsp;К/s were investigated. Structure was characterized by metallography, X-Ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. Corrosion properties were determined by gravimetric and potentiodynamic methods at room temperature. The investigations performed confirm the peritectic formation of stable quasicrystalline decagonal D-phase that coexists with crystalline Al<sub>4</sub>(Co,Cu)<sub>3</sub> and Al<sub>3</sub>(Cu,Co)<sub>2</sub> phases in the structure of Al<sub>65</sub>Co<sub>20</sub>Cu<sub>15</sub> alloy. According to energy dispersive spectroscopy, the stoichiometric composition of D-phase is Al<sub>63</sub>Co<sub>24</sub>Cu<sub>13</sub>. The susceptibility of the Al<sub>65</sub>Co<sub>20</sub>Cu<sub>15</sub> alloy to corrosion significantly decreases with increasing pH from 1.0 (acidic media) to 7.0 (neutral medium). A corrosion rate of the Al<sub>65</sub>Co<sub>20</sub>Cu<sub>15</sub> alloy in the aqueous acidic solutions (pH=1.0) increases in the order HNO<sub>3</sub>®HCl®H<sub>2</sub>SO<sub>4</sub>®H<sub>3</sub>PO<sub>4</sub>. The mass of the specimens decreases in the solutions of H<sub>2</sub>SO<sub>4</sub> or H<sub>3</sub>PO<sub>4 </sub>and increases in the solutions of HNO<sub>3</sub> or HCl which relates to different rate ratios of accumulation and dissolution of corrosion products. The Al<sub>65</sub>Co<sub>20</sub>Cu<sub>15</sub> alloy exhibits the highest corrosion resistance in the NaCl solution (pH=7.0) in which it corrodes under electrochemical mechanism with oxygen depolarization. The better corrosion resistance in sodium chloride solution is achieved due to the formation of passive chemical compounds blocking the surface. Free corrosion potential of the Al<sub>65</sub>Co<sub>20</sub>Cu<sub>15</sub> alloy has value –0.43&nbsp;V, the electrochemical passivity region extends from –1.0 V to –0.4 V, and a corrosion current density amounts to 0.18&nbsp;mА/сm<sup>2</sup>. Depending on media, two typical surface morphologies are revealed after corrosion of quasicrystalline specimens of the Al<sub>65</sub>Co<sub>20</sub>Cu<sub>15</sub> alloy. In the H<sub>2</sub>SO<sub>4</sub> and H<sub>3</sub>PO<sub>4</sub> acidic solutions, clean specimens’ surface due to its homogeneous dissolution is observed except for the more defective areas, such as boundaries of crystalline Al<sub>3</sub>(Cu,Co)<sub>2</sub> phase containing less Co, which dissolve at a higher rate. In the HNO<sub>3</sub>, HCl or NaCl solutions, a porous layer on the surface is formed which is visually revealed as surface darkening. After staying in the NaCl solution, on the surface of the Al<sub>65</sub>Co<sub>20</sub>Cu<sub>15</sub> alloy, the pits are also found due to preferential dissolution of components where the boundaries of Al<sub>3</sub>(Cu,Co)<sub>2</sub> phase and flaws are located.</p> Olena V. Sukhova, Volodymyr A. Polonskyy Copyright (c) 2021 Olena V. Sukhova, Volodymyr A. Polonskyy https://periodicals.karazin.ua/eejp/article/view/17748 Tue, 28 Sep 2021 00:00:00 +0000 Determination of Calibration X-Ray Beam Qualities and Establish a Set of Conversion Coefficients for Calibration of Radiation Protection Devices Used in Diagnostic Radiology https://periodicals.karazin.ua/eejp/article/view/17749 <p>The use of X-ray facilities in calibrating radiation measuring equipment in diagnostic radiology requires an exact knowledge of the radiation field. X-ray spectrums are made narrow beam by proper filtration recommended by several international organizations. In the present study, the experimental determination of X-ray calibration qualities and analysis of conversion coefficients from air Kerma to ambient and personal dose equivalent is carried for X-ray beam irradiator X80-225kV as per ISO narrow spectrum series at Secondary Standard Dosimetry Laboratory (SSDL) in Bangladesh. The X-ray beam involved in half value layer, effective energy, beam homogeneity coefficient and consistency of X-ray production from the generator (kV and mA) is conducted. A discrepancy of half value layer has been observed for N200 beam code by -8.5% which leads to the deviation of effective energy by -7.7% with a standard deviation of 1.3%. The conversion coefficients from the air kerma to dose equivalent that satisfying the condition of ICRU sphere is established to obtain radiation qualities and compared with values referred by other standard laboratories. A deviation of 0.87% has been observed for <em>H*(10)</em> and <em>H</em><em>¢</em><em>(0.07</em>) in between ISO and BCRU empirical relation which is insignificant. A set of conversion coefficients for <em>Hp(10)</em> and <em>Hp(0.0</em>7) has also been calculated for ICRU four element tissue.</p> Tanjim Siddiqua, Md. Shakilur Rahman, Md. Sanaullah, Zohora Akter Mitu, Imran Hossain, Sadeka Sultana Rubai Copyright (c) 2021 Tanjim Siddiqua, Md. Shakilur Rahman, Md. Sanaullah, Zohora Akter Mitu, Imran Hossain, Sadeka Sultana Rubai https://periodicals.karazin.ua/eejp/article/view/17749 Tue, 28 Sep 2021 00:00:00 +0000 Fundamental Physical Properties of LiInS2 and LiInSe2 Chalcopyrite Structured Solids https://periodicals.karazin.ua/eejp/article/view/17750 <p>For the couple of chalcopyrite compounds, we have theoretically studied the various properties for example structural, electronic optical and mechanical properties. The band structure curve, the density of states as well as the total energy have been investigated with the help of ATK-DFT by using the pseudo-potential plane wave method. For the LiInS<sub>2</sub> and LiInSe<sub>2</sub> chalcopyrites, we have found that these compounds possess direct band gap; which is 3.85 eV and 2.61 eV for LiInS<sub>2</sub> and LiInSe<sub>2 </sub>respectively. It shows that the band gap is decreasing from ‘S’ to ‘Se’ as well as the B/G ratio called Pugh’s ratio is 2.10 for LiInS<sub>2 </sub>and 2.61 for LiInSe<sub>2</sub> so these compounds are ductile in nature also these compounds are found to be mechanically stable. The study of this work display that the couple of these chalcopyrite compounds can be the promising candidate for the substitution of absorbing layer in the photovoltaic devices.</p> Jyoti Kumari, Shalini Tomar, Sukhendra Sukhendra, Banwari Lal Choudharya, Upasana Rani Rani, Ajay Singh Verma Copyright (c) 2021 Jyoti Kumari, Shalini Tomar, Sukhendra, Banwari Lal Choudhary, Upasana Rani, Ajay Singh Verma https://periodicals.karazin.ua/eejp/article/view/17750 Tue, 28 Sep 2021 00:00:00 +0000 Synthesis and Characterization of Methylammonium Lead Bromide Perovskite Based Photovoltaic Device https://periodicals.karazin.ua/eejp/article/view/17751 <p>Hybrid electronic devices give a reasonable path for feasible power sources and other further applications due to its easy arrangement, preparation, producing, ease of materials, and less environmental impact. In this paper, we have discussed electrical properties of hybrid bromide perovskite nanoparticles and current progressions in perovskite photovoltaic devices have also been discussed. In order to fabricate, low-temperature solution-processed devices using one-step spin coating methods play a key role in producing uniform thin films. The spin coating technique has been used for the deposition of the precursor solution including methylammonium bromide (MABr) and lead bromide (PbBr2) with molar ratio (3:1) to prepare the thin films onto FTO-substrate. One-step solution processes has been used for deposition of the CH<sub>3</sub>NH<sub>3</sub>PbBr<sub>3</sub> absorber layers and have explained an overview of material composition, deposition technique and the architecture of the device, the selection of charge transport layer and electrode.</p> Shaily Choudhary, Shalini Tomar, Depak Kumar, Sudesh Kumar, Ajay Singh Verma Copyright (c) 2021 Shaily Choudhary, Shalini Tomar, Depak Kumar, Sudesh Kumar, Ajay Singh Verma https://periodicals.karazin.ua/eejp/article/view/17751 Tue, 28 Sep 2021 00:00:00 +0000 Investigations of Lead Free Halides in Sodium Based Double Perovskites Cs2NaBiX6(X=Cl, Br, I): an Ab Intio Study https://periodicals.karazin.ua/eejp/article/view/17752 <p>Despites the excellent merits of lead based perovskite optoelectronic devices; their unstable nature and toxicity still present a bottleneck for practical applications. Double perovskite has emerged as a candidate for optoelectronics and photovoltaic application because of its nontoxic behaviour and stability in air. We have presented ab-initio study of Cs<sub>2</sub>NaBiX<sub>6</sub>(X=Cl, Br, I) lead free halide double perovskites. The calculation is carried out using the FP-LAPW method in the DFT framework within PBE potential using the WIEN2k code. The structural, electronic and optical properties of Cs<sub>2</sub>NaBiI<sub>6</sub>, Cs<sub>2</sub>NaBiBr<sub>6</sub> and Cs<sub>2</sub>NaBiCl<sub>6</sub> have been analysed. We have obtained the band gap of 2.0, 2.6 and 3.7 for Cs2NaBiI<sub>6</sub>, Cs<sub>2</sub>NaBiBr<sub>6</sub> and Cs<sub>2</sub>NaBiCl<sub>6 </sub>respectively. Throughout the study, we have shown that the variation in the structure of double perovskite within Cs<sub>2</sub>NaBiX<sub>6</sub>(X=Cl, Br, I) that leads to the variation in band gap, density of states and in optical properties such as extinction coefficient, absorption spectra, optical reflectivity, dielectric coefficient, refractive index that shows the variety of this material for optoelectronic devices and other purposes.</p> Shaily Choudhary, Shalini Tomar, Depak Kumar, Sudesh Kumar, Ajay Singh Verma Copyright (c) 2021 Shaily Choudhary, Shalini Tomar, Depak Kumar, Sudesh Kumar, Ajay Singh Verma https://periodicals.karazin.ua/eejp/article/view/17752 Tue, 28 Sep 2021 00:00:00 +0000 The Plasma Parameters of Penning Discharge with Negatively Biased Metal Hydride Cathode at Longitudinal Emission of H– Ions https://periodicals.karazin.ua/eejp/article/view/17753 <p>The enhancement of negative ion production in a volume Penning based source could be performed by the application of metal hydride cathode. Hydrogen isotopes are stored there in a chemically bound atomic state and desorbed from the metal hydride under the discharge current impact. Highly vibrationally / rotationally excited molecules H<sub>2</sub>* are formed by recombination of H-atoms at the metallic surface, which then can be easily converted to H<sup>–</sup> by dissociative electron attachment without the pre-excitation of a H<sub>2</sub> molecule in plasma. Changing the discharge properties opens the way of source design simplification by negative ions extraction along the external magnetic field in comparison with traditional volume sources, where the extraction is performed perpendicular to magnetic field. The separation of negative ions from the extracted in longitudinal direction flux of charged particles was performed by an electromagnetic filter basing on numerical calculations of particles trajectories. The dependence of electron temperature and plasma density on the bias potential is carried out by Langmuir probe method. The measurement of electron energy was performed by an electrostatic energy analyzer. It was shown that the yield of H<sup>–</sup> ions depends on the electrical bias on the metal hydride cathode with strong dependences on the plasma electrons temperature. The estimation of the bias potential versus <em>T<sub>e</sub></em> was performed under the assumption of electron Boltzmann distribution near the cathode. The presence of additional groups of electrons with higher energies distorts the behavior of H<sup>–</sup> current, but generally the experimental results are in good agreement with estimation based on the physics behind the Boltzmann distribution. The optimum for the effective extraction of H<sup>–</sup> ions was revealed, when the metal hydride cathode had been electrically biased at -20V and higher, and plasma density reaches the maximum value to 2×10<sup>9</sup>&nbsp;cm<sup>-3</sup>.</p> Ihor Sereda, Yaroslav Hrechko, Ievgeniia Babenko Copyright (c) 2021 Ihor Sereda, Yaroslav Hrechko, Ievgeniia Babenko https://periodicals.karazin.ua/eejp/article/view/17753 Tue, 28 Sep 2021 00:00:00 +0000 Study of the Mechanical Properties of Shell of Fuel Elements from Zr1% Nb Alloys at Radial Stresses Similar to Reactor Conditions https://periodicals.karazin.ua/eejp/article/view/17754 <p>When determining the mechanical properties of ring specimens, a feature of a uniaxial (standard) loading scheme is that the method of applying a load to a specimen is somewhat remote from that to which the pipe walls can be subject in real operating conditions, in particular, these are tubes of fuel element shells. As an alternative loading method, the method of strain of an ring specimen on a cylindrical rod was considered and tested. By compressing the cylindrical rod from the ends, which in this case expanded and exerted pressure on the inner walls of the ring specimen in the radial direction, the specimen was deformed. The plasticity of fuel element shells made of Zr-1%Nb alloy on ring specimens under different loading methods is evaluated: uniaxial tension on half-disk supports, on a cylindrical rod, and on a tapered rod. Uniaxial tensile strain was determined in accordance with the normative documentation for the test method. When testing on a tapered rod, a specimen with a thinned working part was used. For the proposed loading method, the radial strain was measured by the change in the sample diameter. The results of testing the samples on a cylindrical rod were compared with the previously obtained results on half-disc supports and a tapered rod. The method of deformation of a ring specimen on a cylindrical rod makes it possible to obtain higher values of plasticity in comparison with uniaxial tension. In addition, the proposed method of deformation of a sample on a cylindrical rod, in contrast to uniaxial tension, in terms of the nature of the stress state, approaches to the operating reactor conditions.</p> V.I. Savchenko, N.N. Belash, Yevgeniy A. Krainyuk, Viktor N. Voyevodin Copyright (c) 2021 V.I. Savchenko, N.N. Belash, Y.A. Krainyuk, Voyevodin V.N. https://periodicals.karazin.ua/eejp/article/view/17754 Tue, 28 Sep 2021 00:00:00 +0000 Bremsstrahlung Generation by 7.5 Mev Electrons in Converters Made of Different Materials https://periodicals.karazin.ua/eejp/article/view/17755 <p>The present paper shows that, besides the technologically complex water-cooled converters made of Ta or W, a simple and efficient converter in the form of air-cooled Mo and Al plates can be fabricated for a number of tasks. The generation of bremsstrahlung by electrons with the energy of 7.5 MeV in the converter plates made of Ta, W, Cu or Mo and in the Al filter was studied by the Monte Carlo method in the PENELOPE software package. The thicknesses&nbsp; range of the plates made of Ta, W, Cu or Mo was chosen on condition that the total mass thickness of the converter and filter made of Al (in g/mm<sup>2</sup>) provided complete absorption of the primary electrons. It is shown that the photon yields from Mo at mass thicknesses above 25 g/mm<sup>2</sup> are higher than those from Ta and W, but the energy transferred from electrons to BS is lower. With the same mass thicknesses of Ta and W converters, practically all characteristics of bremsstrahlung and the absorbed energy in the target are the same. The conditions for cooling the converter elements with water and air are determined for the level of heat release in the converter up to 10 kW. The minimum dimensions of the electron-irradiated region of Ta and Mo converters, cooled by water, are determined. It is shown that with the really existing air compressors taken into account, the permissible heat release of air-cooled Mo converters should not exceed 4 kW.</p> Vladimir G. Rudychev, Nikolay A. Azarenkov, Igor A. Girka, Yegor V. Rudychev Copyright (c) 2021 Vladimir G. Rudychev, Nikolay A. Azarenkov, Igor A. Girka, Yegor V. Rudychev https://periodicals.karazin.ua/eejp/article/view/17755 Tue, 28 Sep 2021 00:00:00 +0000 Formation of Optical Images with Synchrotron Radiation Flux of Relativistic Electrons in the X-Ray Generator "Nestor" https://periodicals.karazin.ua/eejp/article/view/17756 <p>When setting up physical experiments involving the use of the polarization properties of synchrotron radiation (SR) or a monoenergetic photon beam, detailed calculation of the spectral angular distribution of SR and its polarization components is of interest. Consideration of the electron beam size shows that in real conditions the radiation propagating in the plane of the equilibrium orbit will not be completely polarized, and the shape and dimensions of the angular distribution of radiation will be distorted. The motion of electrons in the uniform magnetic field and SR of the beam of relativistic particles in the storage ring of "NESTOR" are considered. The effect of the size of the electron beam with the energy of <em>E</em>=225&nbsp;MeV in the 6-dimensional space on the formation of images of the flux of quanta of SR is analyzed. It is shown that the main contribution to the formation of images is made by the two-dimensional distribution of particles along the vertical direction axis and vertical oscillations. A software simulation code has been developed, the use of which made it possible to simulate the process of optical image formations by the flux of SR quanta (Этого предложения нет в русской аннотации). The formation of images of the radiation of electrons with an energy of <em>E</em>=225&nbsp;MeV with change in the longitudinal distance <em>L</em> to the registration plane is considered. It is determined that at small longitudinal distances the main contribution to the image is made by the vertical distribution of particles in the beam. With an increase in the basic distance <em>L</em>, the contribution of the distribution of particles over vertical oscillations increases, which becomes decisive for large <em>L </em>value. Numerical simulation of image formation has been carried out. For the base distance of 300&nbsp;cm and beam parameters with the vertical root mean square size &nbsp;of 0.2&nbsp;mm and a vertical root mean square size of 0.15&nbsp;mrad, the family of angular distributions is presented in the form of two-dimensional histograms for wavelengths , , , where , is the critical wavelength of SR. The dimensions of the optical window are obtained, the size of which makes it possible to reliably register the entire flux of SR quanta for the indicated registration characteristics.</p> Aleksandr Mazmanishvili, Nataliya Moskalets Copyright (c) 2021 Aleksandr Mazmanishvili, Nataliya Moskalets https://periodicals.karazin.ua/eejp/article/view/17756 Tue, 28 Sep 2021 00:00:00 +0000 The Impact of Pulse Plasma Treatment on the Operating Characteristics of Steel 40X10C2M: Experiment and Numerical Simulations https://periodicals.karazin.ua/eejp/article/view/17757 <p>This paper presents a study of operating characteristics of steel 40X10C2M after treatment it of high-energy plasma pulses. The steel is used to manufacture the elements of ships' power plants. For pulsed plasma treatment of steel samples, we used an electrothermal plasma accelerator (ETPA). A high-current pulsed high-pressure arc discharge was initiated in a restricted dielectric chamber of ETPA. The discharge duration was 1.4 ms, the maximum current reached the value of 5 kA, the discharge voltage was up to 5 kV. We investigated the microhardness and microstructure of the processed (modified) layer and determined the optimal parameters of steel processing that provide the best characteristics of the modified layer when the microhardness increases by ≈ 5 times. Microhardness maxima were discovered in the depth of the modified layer. The paper studies the possibilities of controlling the maxima localization to form the desired performance characteristics of the treated layer. Mathematical modeling of rapid pulsed heating of the steel surface layer is performed within the framework of the two-phase "melt-solid" model, taking into account the dynamics of the thermodynamic characteristics of steel. For this purpose, we used the classical equation of thermal conductivity with varying steel parameters: density, heat capacity, and coefficient of thermal conductivity during the transition of a substance from the liquid to the solid phase. Within the chosen mathematical model, numerical calculations of the rapidly pulsed heating phenomenon of the steel surface were performed, taking into account melting and solidification in the Comsol Multiphysics package using the finite element method. The numerical simulation results are in good agreement with the experimental distribution of the microhardness of the treated steel layer deep into the sample.</p> Nikolay A. Savinkov, Oleh M. Bulanchuk, Aleksander A. Bizyukov Copyright (c) 2021 Nikolay A. Savinkov, Oleh M. Bulanchuk, Aleksander A. Bizyukov https://periodicals.karazin.ua/eejp/article/view/17757 Tue, 28 Sep 2021 00:00:00 +0000 Research and Development of Fuel Rods Metallurgically Bonded with Fuel Cladding for Nuclear Installations https://periodicals.karazin.ua/eejp/article/view/17758 <p>The design and scheme for manufacturing fuel rods metallurgically bonded with ribbed aluminum claddings using hot isostatic pressing and contact-reactive brazing are presented. It is shown that the developed scheme can be used both for production of dispersive fuels and high-density fuels based on uranium alloys. The results of investigations of brazed joints of aluminum cladding with a matrix composition based on aluminum and with samples of E110 alloy through copper and silumin coatings are presented. The results of research of brazed joints of an aluminum cladding with an aluminum-based matrix composition and samples of zirconium alloy E110 made through copper and silumin coating are presented. The strength of brazed joints, composition of diffusion layers formed as a result of contact-reactive brazing in a high vacuum have been determined. The modes of hot isostatic pressing that provide crimping of the ribbed cladding of fuel pellets and rods and obtaining a metallurgical bonding between their surfaces have been defined. It is shown that satisfactory bond strength is provided starting from the temperature of 610&nbsp;°С. The maximum strength values obtained on the compounds Al-(Al+12% Si)-Zr and Al-Cu-Zr are 57.0&nbsp;MPa and 55.3&nbsp;MPa respectively. The fracture of the of aluminum samples joints, obtained with the Cu layer at a temperature of 620&nbsp;°C, occurs on threaded joints at the strength value of 82&nbsp;MPa. The results of research of the composition of diffusion layers formed by brazing compounds Al-(Al + 12% Si)-Zr and Al-Cu-Zr are presented. It was established that hot pressing provides the best results for manufacturing of fuel rod dummies in the studied range of modes at a temperature of 630&nbsp;°C, a pressure of 380&nbsp;MPa and exposure of 20 minutes.</p> Nikolay N. Belash, Anton V. Kushtym, Vladimir V. Zigunov, Elena A. Slabospytska, Gennadіy А. Holomeyev, Ruslan L. Vasilenko, Аleksandr I. Tymoshenko Copyright (c) 2021 Nikolay N. Belash, Anton V. Kushtym, Vladimir V. Zigunov, Elena A. Slabospytska, Gennadіy А. Holomeyev, Ruslan L. Vasilenko, Аleksandr I. Tymoshenko https://periodicals.karazin.ua/eejp/article/view/17758 Tue, 28 Sep 2021 00:00:00 +0000 Degradation Mechanisms of the Detector Properties of CdTe and CdZnTe Under the Influence of Gamma Irradiation https://periodicals.karazin.ua/eejp/article/view/17759 <p>This work is devoted to the study of the mechanisms of the influence of radiation defects, arising under the influence of gamma irradiation, on the change in resistivity ρ, lifetime of nonequilibrium electrons τ<sub>n</sub> and holes τ<sub>p</sub>, in CdTe:Cl and Cd<sub>0.9</sub>Zn<sub>0.1</sub>Te as well as the collection efficiency η of uncooled radiation detectors based on these materials, by computer simulation method. Radiation defects, that are corresponded by deep energy levels in the band gap, act as trapping centers of nonequilibrium charge carriers, noticeably affect the degree of compensation by changing ρ of the detector material, the recombination processes by decreasing τ<sub>n</sub> and τ<sub>p</sub>, what ultimately can cause degradation of the charges collection efficiency η. The specific reasons for the deterioration of the detector properties of CdTe:Cl and Cd<sub>0.9</sub>Zn<sub>0.1</sub>Te under the influence of gamma irradiation were identified, and the main factors leading to complete degradation of the recording ability of detectors based on these semiconductors during their bombardment by <sup>60</sup>Co gamma quanta were determined. The gradual degradation of the spectroscopic performance of CdTe:Cl-based detectors during gamma irradiation occurs due to the continuous formation of cadmium vacancies V<sub>Cd</sub> and acceptor complexes V<sub>Cd</sub> – Cl, which continuously shift Fermi level towards valence band and decrease ρ. The complete performance degradation of CdTe detectors takes place mainly due to the capture of nonequilibrium electrons at energy level of interstitial tellurium Te(I). The invariable spectroscopic properties of CdZnTe-based sensors under gamma irradiation up to 25 kGy occur due to the mechanism of radiative self-compensation by formation of substitutional defect Te<sub>Zn</sub>. At the final stage of irradiation, a sharp deterioration in the detector properties of CdZnTe occurs, mainly due to the capture and recombination of nonequilibrium charge carriers at the level of the Te(I) defect. The different radiation resistances of CdZnTe and CdTe:Cl can be explained by different behavior of Fermi level E<sub>F</sub> in these semiconductors under gamma irradiation. E<sub>F</sub> in CdZnTe under radiation exposure remains near the middle of band gap, and in CdTe it drifts to the valence band. The rate of capture and recombination through Te(I) donor level in CdTe:Cl is lower than in CdZnTe due to the larger difference between the Fermi level and the radiation defect Te(I) level in cadmium telluride. Thereby, the complete degradation of the CdTe:Cl detector occurs at a higher concentration of radiation defect Te(I), and hence after a higher irradiation dose of 50 kGy compared with a dose of 30 kGy required for degradation of CdZnTe detector properties.</p> Alexandr I. Kondrik Copyright (c) 2021 Alexandr I. Kondrik https://periodicals.karazin.ua/eejp/article/view/17759 Tue, 28 Sep 2021 00:00:00 +0000 Influence Of Formation Conditions, Subsequent Annealing and Ion Irradiation on the Properties of Nanostructured Coatings Based on Amorphous Carbon with Gold, Silver and Nitrogen Additives https://periodicals.karazin.ua/eejp/article/view/17767 <p>Nanostructured coatings based on amorphous carbon and carbon-doped with gold, silver, and nitrogen were obtained by the pulsed vacuum-arc method. Carbon coatings have been annealed in a vacuum as well as treated with argon ions. The alloying of carbon coatings with elements that do not form chemical bonds with the carbon matrix (Ag, Au) leads to the formation of gold or silver nanocrystallites with sizes of 2&nbsp;‑&nbsp;20&nbsp;nm in the matrix of amorphous carbon, whose density depends on the concentration of the doping element. Annealing of silver-doped carbon coatings leads to the formation of islands on the surface with the size of the order of micrometers. This is due to the silver diffusion and coalescence of small islands into larger ones. The HRTEM method discovered the effect of twinning in carbon nanocrystallites after vacuum annealing as well as silver and gold in the initial state (the formation of single-crystal regions with an altered orientation of the crystal structure) in the amorphous carbon matrix. Analysis of Raman spectra of pure carbon coating and silver-doped showed that the addition of silver leads to a decrease in sp3-phase in the carbon matrix. This effect is particularly evident in the nature of changes in the spectra after vacuum annealing at 600 ºC. The addition of nitrogen in the carbon coating leads to an increase in the sp2&nbsp;‑&nbsp;phase fraction, and additional annealing leads to a significant increase in the D - peak intensity and formation of clusters of the order of 5&nbsp;‑&nbsp;15 nm, which are not localized but fill the entire space. Analysis of the coating a-C: Au irradiation with argon ions shows that the number of nanopitches decreased after ion irradiation, simultaneously decreased surface roughness degree, besides, decreased electrical conductivity of the coating as a result of decreased gold content. It was found that the conditions of nanostructured coatings and their subsequent processing allow controlling the properties of nanocoatings (structure, size of nanoparticles, surface topography, and electrical conductivity).</p> Aleksandr Kolpakov, Aleksandr Poplavsky, Maksim Yapryntsev, Vseslav Novikov, Sergey Manokhin, Igor Goncharov, Marina Galkina, Vyacheslav Beresnev Copyright (c) 2021 Aleksandr Kolpakov, Aleksandr Poplavsky, Maksim Yapryntsev, Vseslav Novikov, Sergey Manokhin, Igor Goncharov, Marina Galkina, Vyacheslav Beresnev https://periodicals.karazin.ua/eejp/article/view/17767 Tue, 28 Sep 2021 00:00:00 +0000 Beam Scanning Controller for Proton-Beam Writing https://periodicals.karazin.ua/eejp/article/view/17768 <p>A scanning control system of the ion beam of MeV energies has been developed for the nuclear scanning microprobe and proton-beam writing channel as a part of accelerator-analytical complex based on the Sokol electrostatic accelerator of the Institute of Applied Physics of the National Academy of Sciences of Ukraine. The system was put into operation to replace the obsolete one based on microcontrollers. The scanning control system is based on a National Instruments reconfigurable module with a Field Programmable Gate Array. The module operates in real time and is connected to a personal computer by a high-speed PCI-Express interface with data buffering. The system provides two main modes of operation: exposure of sample areas with a given profile and raster secondary electrons imaging of the sample or a calibration grid. Profile exposure is possible both in raster and functional scanning modes. Automatic calibration of the profile scale and scan raster is also implemented. Using of reconfigurable logic makes it possible to quickly adjust the system to the conditions of a particular experiment and the available equipment. The hardware capabilities of the scanning control system allows in the future to connect up to 4 spectrometric ADC for mapping the elemental composition of samples using Proton Induced X-ray Emission and Proton Backscattering. The first experiments on the irradiation of polymethylmethacrylate have been carried out; images of the obtained microstructures taken with a scanning electron microscope are shown. The aim of this work is to develop a control system for scanning a high-energy focused beam in proton beam writing technique to create small-sized structures for special purposes, as well as to demonstrate the efficiency of the developed system.</p> Sergey V. Kolinko, Ivan S. Kolinko, Hlib E. Polozhii, Aleksandr G. Ponomarev Copyright (c) 2021 S.V. Kolinko, I.S. Kolinko, H.E. Polozhii, A.G. Ponomarev https://periodicals.karazin.ua/eejp/article/view/17768 Tue, 28 Sep 2021 00:00:00 +0000 Influence of the Order of Ion Implantation on Luminescent Spectrum of ZnSe Nanocrystals https://periodicals.karazin.ua/eejp/article/view/17769 <p>The paper presents the results of mathematical treatment of the luminescent spectra of ZnSe nanocrystals. The samples were formed by the implantation of 150 keV Zn<sup>+</sup> and 170 keV Se<sup>+</sup> ions in silicon dioxide layer obtained by oxidation of a silicon substrate. We analyzed two sorts of the samples obtained with different implantation sequences: Zn<sup>+</sup> were implanted first, and Se<sup>+</sup> implanted next (sample A); reverse sequence with Se<sup>+</sup> implanted at the beginning (sample B). The spectra obtained for different implantation sequences A and B differed from each other. It was found that besides the intensive evident bands with maxima at 2.3 eV (540 nm) and 2.85 eV (430 nm), which were associated with ZnSe intrinsic luminescent centers, there were two bands with maxima at 1.9 eV (650 nm) and 2.6 eV (480 nm), which were related to intrinsic SiO<sub>2</sub> defects. Hereby the effect of the medium (silicon dioxide matrix) on luminescent spectra of SiO<sub>2</sub> films with ZnSe nanocrystals formed by ion implantation was demonstrated. Mathematical treatment of the band shape with a maximum of 2.85 eV showed that the parameters such as full width at half maximum, skewness and kurtosis indicated the dependence of size distribution of ZnSe nanoparticles on the implantation sequence of ions. The results are in a good agreement with the data of Transmission Electron Microscopy.</p> Anna Boichenko, Sergiy Kononenko, Fadei Komarov, Oganes Kalantaryan, Vitaliy Zhurenko, Stanislav Avotin, Nikolay Rokhmanov Copyright (c) 2021 Anna Boichenko, Sergiy Kononenko, Fadei Komarov, Oganes Kalantaryan, Vitaliy Zhurenko, Stanislav Avotin, Nikolay Rokhmanov https://periodicals.karazin.ua/eejp/article/view/17769 Tue, 28 Sep 2021 00:00:00 +0000 Fast Electromagnetic Waves on Metamaterial’s Boundary: Modeling of Gain https://periodicals.karazin.ua/eejp/article/view/17771 <p>The paper presents the results of the study of properties of&nbsp;fast surface electromagnetic waves that propagate along the flat interface between the active metamaterial and air (or vacuum). The case of homogeneous and isotropic metamaterial is considered. The dispersion properties, the wave spatial attenuation, the phase and group velocities, as well as the spatial distribution of the electromagnetic field of the eigen TE and TM modes of such a waveguide structure are studied in the frequency range where the metamaterial has a simultaneously negative permittivity and permeability. It is shown that fast surface electromagnetic waves can exist in this waveguide structure and their properties are studied. It is shown that the phase speed of TM mode is several times higher than the speed of light in vacuum, while the phase speed of TE mode is slightly higher than the speed of light in vacuum. The TM mode is a direct wave in which the phase and group velocities have the same direction. It is obtained that the group velocity of the TM mode varies from zero to the about half of speed of light in vacuum, and reaches a minimum at a certain value of wave frequency, which depends on the characteristics of the metamaterial. It is shown that the penetration depth of the TM mode into the metamaterial is much smaller than into the vacuum. The TE mode is a backward wave with opposite directed phase and group velocities. The absolute value of the group velocity of the TE mode is about six times less than the speed of light in vacuum. In contrast to the TM mode the penetration depth of the TE mode into the metamaterial is much greater than in vacuum. The obtained properties of the fast surface electromagnetic waves can be used for modeling and design of modern generation and amplification devices containing metamaterials.</p> Viktor K. Galaydych, Alexandr E. Sporov, Volodymyr P. Olefir, Mykola O. Azarenkov Copyright (c) 2021 V.K. Galaydych, A.E. Sporov, V.P. Olefir, M.O. Azarenkov https://periodicals.karazin.ua/eejp/article/view/17771 Tue, 28 Sep 2021 00:00:00 +0000 Determination of Uranium Isotopic Ratios by HRGS Using Various Efficiency Calibration Approaches https://periodicals.karazin.ua/eejp/article/view/17781 <p>The effect of various efficiency calibration approaches on the value and source of the HRGS measurement uncertainty of <sup>234</sup>U/<sup>238</sup>U, <sup>235</sup>U/<sup>238</sup>U, <sup>234</sup>U/<sup>235</sup>U&nbsp;isotopic ratios for the purposes of technological control, nuclear forensics, and environmental monitoring has been studied. The Canberra Broad Energy Germanium detector BEGe3830 and five samples of uranium certified reference materials CRM 969 and CRM 146 with a content of <sup>235</sup>U/U ranging from 0.7 to 20.0 wt. % have been used. To calculate the uranium isotope ratios, the acquired gamma spectra were processed using: commercial MGAU (LLNL), FRAM (LANL), ISOCS software (Canberra/Mirion Technologies), based on intrinsic and absolute efficiency calibration approaches. It has been found that maximum relative biases, for the <sup>234</sup>U/<sup>238</sup>U and <sup>234</sup>U/<sup>235</sup>U isotopic ratios determined using the MGAU \ FRAM \ ISOCS software, are ~ 25 % \ ~ 10 % \ ~ 10 %, and the random uncertainty is varied within ± [18-25 % \ 2-15 % \ &lt;=3 %], respectively. In the case of <sup>234</sup>U/<sup>238</sup>U isotopic ratio determination using the MGAU \ FRAM \ ISOCS software, maximum relative biases come to ~ 3 % \ ~ 4 % \ ~ 1 %, and the random uncertainty values decrease to ± [1 % \ 1 % \ 1 %], respectively. In the present paper, we propose a combined intrinsic efficiency calibration approach with the use of the polynomial functions for the analytical description of the relation<em> ε<sub>rel.</sub>i(E<sub>i</sub>)</em>. In this approach maximum relative biases, in the determination of the <sup>234</sup>U/<sup>238</sup>U and <sup>234</sup>U/<sup>235</sup>U&nbsp;isotopic ratios is 2.7 % at a random uncertainty of &lt;= 1 %, &nbsp;and in the case of the <sup>234</sup>U/<sup>238</sup>U&nbsp;ratio a maximum relative deviation is 0.5 % at a random uncertainty of &lt;= 0.7 %.</p> Dmytro V. Kutnii , Dmytro D. Burdeynyi Copyright (c) 2021 Dmytro V. Kutnii, Dmytro D. Burdeynyi, Stanislav A. Vanzha, Natalia V. Rud https://periodicals.karazin.ua/eejp/article/view/17781 Thu, 28 Oct 2021 00:00:00 +0000