Pub Date : 2024-05-07DOI: 10.1134/s1027451024020344
U. L. Mishigdorzhiyn, B. A. Dyshenov, A. P. Semenov, N. S. Ulakhanov, B. E. Markhadayev
Abstract
The application of mathematical models and artificial neural networks for predicting the properties of diffusion coatings created by thermal–chemical treatment based on the boroaluminizing process is considered. The formalization and analysis of forecasting experimental results are conducted. Building computer models for prediction based on experimental data of the boroaluminizing process with high accuracy is a solvable task when using artificial neural networks such as a multilayer perceptron. Testing the number of hidden layers and the number of neurons in them revealed the highest correlation coefficient R = 0.99993 for an artificial neural network using two hidden layers with ten and six neurons, respectively. The highest efficiency can be achieved using the hyperbolic tangent activation function.
摘要 本研究考虑了数学模型和人工神经网络在预测基于硼铝化工艺的热化学处理扩散涂层性能方面的应用。对预测实验结果进行了形式化和分析。使用多层感知器等人工神经网络，可以根据硼铝化工艺的实验数据建立高精度预测计算机模型。对隐藏层数和其中的神经元数量进行测试后发现，使用分别有 10 个和 6 个神经元的两个隐藏层的人工神经网络的相关系数 R = 0.99993 最高。使用双曲正切激活函数的效率最高。
{"title":"Prediction of the Thickness of a Boroaluminized Layer Using an Artificial Neural Network","authors":"U. L. Mishigdorzhiyn, B. A. Dyshenov, A. P. Semenov, N. S. Ulakhanov, B. E. Markhadayev","doi":"10.1134/s1027451024020344","DOIUrl":"https://doi.org/10.1134/s1027451024020344","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The application of mathematical models and artificial neural networks for predicting the properties of diffusion coatings created by thermal–chemical treatment based on the boroaluminizing process is considered. The formalization and analysis of forecasting experimental results are conducted. Building computer models for prediction based on experimental data of the boroaluminizing process with high accuracy is a solvable task when using artificial neural networks such as a multilayer perceptron. Testing the number of hidden layers and the number of neurons in them revealed the highest correlation coefficient <i>R</i> = 0.99993 for an artificial neural network using two hidden layers with ten and six neurons, respectively. The highest efficiency can be achieved using the hyperbolic tangent activation function.</p>","PeriodicalId":671,"journal":{"name":"Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140883478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-07DOI: 10.1134/s1027451024020162
N. V. Novikov, N. G. Chechenin, A. A. Shirokova
Abstract
In this paper, we study the anisotropic properties of a layer of carbon nanotubes upon electron reflection. Only a small proportion of the incident electrons is found to be reflected from a target with a surface layer of oriented carbon nanotubes. Reflection occurs only from a layer of horizontally oriented nanotubes at an incidence angle greater than 80° and vertically oriented nanotubes at an incidence angle less than 10°. The effect is explained by the peculiarities of the formation of an electron flow in the surface layers of the target.
{"title":"Features of Electron Reflection by a Layer of Carbon Nanotubes","authors":"N. V. Novikov, N. G. Chechenin, A. A. Shirokova","doi":"10.1134/s1027451024020162","DOIUrl":"https://doi.org/10.1134/s1027451024020162","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>In this paper, we study the anisotropic properties of a layer of carbon nanotubes upon electron reflection. Only a small proportion of the incident electrons is found to be reflected from a target with a surface layer of oriented carbon nanotubes. Reflection occurs only from a layer of horizontally oriented nanotubes at an incidence angle greater than 80° and vertically oriented nanotubes at an incidence angle less than 10°. The effect is explained by the peculiarities of the formation of an electron flow in the surface layers of the target.</p>","PeriodicalId":671,"journal":{"name":"Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140883470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-07DOI: 10.1134/s1027451024020253
A. N. Dudin, V. Yu. Yurina, V. V. Neshchimenko, M. M. Mikhailov, S. A. Yuriev, A. N. Lapin
Abstract
A comparative analysis of the diffuse reflectance spectra and their changes after irradiation with electrons with an energy of 30 keV of coatings based on polymethylphenylsiloxane resin and pigment powders of two-layer hollow ZnO/SiO2 particles is carried out. The analysis is performed in situ in the range of 250–2500 nm. The samples are irradiated using a Spectrum space-conditions simulator. The radiation resistance of the studied coatings based on two-layer hollow ZnO/SiO2 particles is estimated relative to coatings based on ZnO polycrystals by analyzing the difference diffuse reflectance spectra obtained by subtracting the spectra after irradiation from the spectra of the unirradiated samples. It is found that the intensity of the induced absorption bands in coatings based on hollow ZnO/SiO2 particles is less than in coatings based on ZnO microparticles, and the radiation resistance when estimating changes in the integral absorption coefficient of solar radiation (ΔαS) is twice as high. The increase in the radiation resistance is probably determined by the different nature of defect accumulation: in the case of solid microparticles, defects can accumulate inside grains; in hollow particles, the accumulation of defects can occur only within the thin shell of the sphere.
{"title":"Changes in the Optical Properties of Coatings Based on Hollow ZnO/SiO2 Particles under Electron Irradiation","authors":"A. N. Dudin, V. Yu. Yurina, V. V. Neshchimenko, M. M. Mikhailov, S. A. Yuriev, A. N. Lapin","doi":"10.1134/s1027451024020253","DOIUrl":"https://doi.org/10.1134/s1027451024020253","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A comparative analysis of the diffuse reflectance spectra and their changes after irradiation with electrons with an energy of 30 keV of coatings based on polymethylphenylsiloxane resin and pigment powders of two-layer hollow ZnO/SiO<sub>2</sub> particles is carried out. The analysis is performed in situ in the range of 250–2500 nm. The samples are irradiated using a Spectrum space-conditions simulator. The radiation resistance of the studied coatings based on two-layer hollow ZnO/SiO<sub>2</sub> particles is estimated relative to coatings based on ZnO polycrystals by analyzing the difference diffuse reflectance spectra obtained by subtracting the spectra after irradiation from the spectra of the unirradiated samples. It is found that the intensity of the induced absorption bands in coatings based on hollow ZnO/SiO<sub>2</sub> particles is less than in coatings based on ZnO microparticles, and the radiation resistance when estimating changes in the integral absorption coefficient of solar radiation (Δα<sub><i>S</i></sub>) is twice as high. The increase in the radiation resistance is probably determined by the different nature of defect accumulation: in the case of solid microparticles, defects can accumulate inside grains; in hollow particles, the accumulation of defects can occur only within the thin shell of the sphere.</p>","PeriodicalId":671,"journal":{"name":"Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140883477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-07DOI: 10.1134/s1027451024020058
G. G. Bondarenko, V. I. Kristya, D. O. Savichkin, M. R. Fisher
Abstract
We propose a model for a low-current gas discharge in a mixture of argon and mercury vapor in the presence of a thin dielectric film on the surface of a cathode. The model takes into account that in such a mixture, a significant contribution to ionization of the working gas can be made by the ionization of mercury atoms during their collisions with metastable excited argon atoms. Positive charges accumulate in the discharge on the surface of the film, creating an electric field in the dielectric sufficient to induce field electron emission from the metal substrate of the electrode into the dielectric. These electrons are accelerated in the film by an electric field and can exit it into the discharge volume. This increases the effective ion–electron emission yield of the cathode. The temperature dependences of the discharge characteristics show that due to a rapid decrease in the concentration of mercury vapor in the mixture with decreasing temperature, the electric-field strength in the discharge gap and the discharge voltage increase. The presence of a thin dielectric film on the cathode can improve its emission properties and significantly decrease the discharge voltage. These phenomena result in a decrease in the energy of ions and atoms bombarding the cathode surface and, consequently, a reduction in the intensity of cathode sputtering in the discharge.
{"title":"Simulating the Effect of Field Electron Emission from a Cathode with a Thin Dielectric Film on Its Sputtering in a Gas Discharge in an Argon and Mercury Vapor Mixture","authors":"G. G. Bondarenko, V. I. Kristya, D. O. Savichkin, M. R. Fisher","doi":"10.1134/s1027451024020058","DOIUrl":"https://doi.org/10.1134/s1027451024020058","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>We propose a model for a low-current gas discharge in a mixture of argon and mercury vapor in the presence of a thin dielectric film on the surface of a cathode. The model takes into account that in such a mixture, a significant contribution to ionization of the working gas can be made by the ionization of mercury atoms during their collisions with metastable excited argon atoms. Positive charges accumulate in the discharge on the surface of the film, creating an electric field in the dielectric sufficient to induce field electron emission from the metal substrate of the electrode into the dielectric. These electrons are accelerated in the film by an electric field and can exit it into the discharge volume. This increases the effective ion–electron emission yield of the cathode. The temperature dependences of the discharge characteristics show that due to a rapid decrease in the concentration of mercury vapor in the mixture with decreasing temperature, the electric-field strength in the discharge gap and the discharge voltage increase. The presence of a thin dielectric film on the cathode can improve its emission properties and significantly decrease the discharge voltage. These phenomena result in a decrease in the energy of ions and atoms bombarding the cathode surface and, consequently, a reduction in the intensity of cathode sputtering in the discharge.</p>","PeriodicalId":671,"journal":{"name":"Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140883561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-07DOI: 10.1134/s1027451024020307
O. K. Kamynina, S. G. Vadchenko, I. D. Kovalev, D. V. Prokhorov, D. E. Andreev, A. N. Nekrasov
Abstract
Layered composite materials based on niobium and cermet are produced via the self-propagating high-temperature synthesis of preliminarily structured samples using metal foils (Ti, Nb, Ta, Ni) and reaction tapes (Ti + 1.7B) and (5Ti + 3Si). The reaction tapes for synthesis are produced by rolling powder mixtures. The microstructure, and elemental and phase compositions of the synthesized multilayer composite materials are studied by scanning electron microscopy and X-ray phase analysis. Particular attention is paid to the formation of intermediate layers and surface modification occurring during combustion. The strength characteristics of the synthesized materials are determined according to the three-point loading scheme at temperatures of 1100°C. Analysis of the obtained materials shows that joining in the combustion mode of metal foils and reaction tapes is provided due to reaction diffusion, mutual impregnation, and chemical reactions occurring in the reaction tapes and on the surface of the metal foils. The formation of thin intermediate layers in the form of cermet and eutectic solutions provides the synthesized multilayer materials with good strength properties up to 87 MPa at 1100°C. These results are of interest for the development of structural materials operating under extreme conditions.
{"title":"Layered Niobium-Cermet Composite Material","authors":"O. K. Kamynina, S. G. Vadchenko, I. D. Kovalev, D. V. Prokhorov, D. E. Andreev, A. N. Nekrasov","doi":"10.1134/s1027451024020307","DOIUrl":"https://doi.org/10.1134/s1027451024020307","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Layered composite materials based on niobium and cermet are produced via the self-propagating high-temperature synthesis of preliminarily structured samples using metal foils (Ti, Nb, Ta, Ni) and reaction tapes (Ti + 1.7B) and (5Ti + 3Si). The reaction tapes for synthesis are produced by rolling powder mixtures. The microstructure, and elemental and phase compositions of the synthesized multilayer composite materials are studied by scanning electron microscopy and X-ray phase analysis. Particular attention is paid to the formation of intermediate layers and surface modification occurring during combustion. The strength characteristics of the synthesized materials are determined according to the three-point loading scheme at temperatures of 1100°C. Analysis of the obtained materials shows that joining in the combustion mode of metal foils and reaction tapes is provided due to reaction diffusion, mutual impregnation, and chemical reactions occurring in the reaction tapes and on the surface of the metal foils. The formation of thin intermediate layers in the form of cermet and eutectic solutions provides the synthesized multilayer materials with good strength properties up to 87 MPa at 1100°C. These results are of interest for the development of structural materials operating under extreme conditions.</p>","PeriodicalId":671,"journal":{"name":"Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140883564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-07DOI: 10.1134/s1027451024020228
A. A. Abduvayitov, D. A. Tashmukhamedova, B. E. Umirzakov, A. T. Mamadalimov
Abstract
Using the methods of Auger electron spectroscopy, scanning electron microscopy, and measuring the angular dependences of the coefficient of inelastically reflected electrons, changes in the morphology, composition, and structure of CaF2 surface layers under electron bombardment with an energy of Ee = 1–8 keV are studied. The composition of the CaF2 surface changes noticeably at Ee = 2–3 keV and an electron dose of D ≥ 1018 cm–2. It is found that at a dose of less than 1018 cm–2, electrons are incident on separate sections of the CaF2 film. As D increases, the sizes of these sections increase, and starting from D = 8 × 1018 cm–2, the boundaries of neighboring sections overlap. The surface is completely covered with Ca atoms. After annealing at 900 K, a single-crystal Ca film is formed. At Ee = 3 keV, the thickness of the Ca film is ~25–30 Å.
摘要 利用欧杰电子能谱、扫描电子显微镜和测量非弹性反射电子系数的角度相关性等方法，研究了在能量为 Ee = 1-8 keV 的电子轰击下 CaF2 表层的形态、组成和结构的变化。在 Ee = 2-3 keV 和电子剂量 D ≥ 1018 cm-2 时，CaF2 表面的组成发生了明显变化。研究发现，当电子剂量小于 1018 cm-2 时，电子分别入射到 CaF2 薄膜的不同部分。随着 D 的增大，这些部分的尺寸也随之增大，从 D = 8 × 1018 cm-2 开始，相邻部分的边界开始重叠。表面完全被钙原子覆盖。在 900 K 退火后，形成了单晶 Ca 膜。在 Ee = 3 keV 时，钙膜的厚度约为 25-30 Å。
{"title":"Effect of Electron Bombardment on the Composition and Structure of CaF2/Si(111) Films","authors":"A. A. Abduvayitov, D. A. Tashmukhamedova, B. E. Umirzakov, A. T. Mamadalimov","doi":"10.1134/s1027451024020228","DOIUrl":"https://doi.org/10.1134/s1027451024020228","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Using the methods of Auger electron spectroscopy, scanning electron microscopy, and measuring the angular dependences of the coefficient of inelastically reflected electrons, changes in the morphology, composition, and structure of CaF<sub>2</sub> surface layers under electron bombardment with an energy of <i>E</i><sub><i>e</i></sub> = 1–8 keV are studied. The composition of the CaF<sub>2</sub> surface changes noticeably at <i>E</i><sub><i>e</i></sub> = 2–3 keV and an electron dose of <i>D</i> ≥ 10<sup>18</sup> cm<sup>–2</sup>. It is found that at a dose of less than 10<sup>18</sup> cm<sup>–2</sup>, electrons are incident on separate sections of the CaF<sub>2</sub> film. As <i>D</i> increases, the sizes of these sections increase, and starting from <i>D</i> = 8 × 10<sup>18</sup> cm<sup>–2</sup>, the boundaries of neighboring sections overlap. The surface is completely covered with Ca atoms. After annealing at 900 K, a single-crystal Ca film is formed. At <i>E</i><sub><i>e</i></sub> = 3 keV, the thickness of the Ca film is ~25–30 Å.</p>","PeriodicalId":671,"journal":{"name":"Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140883475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-07DOI: 10.1134/s1027451024020071
V. S. Kovivchak, S. A. Matyushenko
Abstract
The features of formation of surface morphology of chlorinated polyvinyl chloride (pure and with the addition of the catalyst—ferrocene) under the influence of a high-power ion beam of nanosecond duration after the preliminary pulsed laser treatment of the polymer surface have been investigated. It was found that the morphology of the irradiated surface of chlorinated polyvinyl chloride after pulsed laser surface pretreatment differs significantly from the morphology of the irradiated surface of chlorinated polyvinyl chloride after preliminary stationary heat treatment. For pure chlorinated polyvinyl chloride, pulsed laser pretreatment with increasing power leads to an increase in the porosity of the surface layer after high-power ion beam irradiation, whereas different surface morphologies, including fibers (including polymer fibers) of different diameters, can be obtained for the pre-stationary thermal treatment of this polymer. Pre-stationary thermal pretreatment of chlorinated polyvinyl chloride with the addition of ferrocene (Fe(C5H5)2) leads to a decrease in the diameter of the formed carbon nanofibers (with an increase in the treatment temperature). During the pulsed laser pretreatment, an increase in the porosity of the treated layer and a slight increase in the proportion of nanofibers of a larger diameter are observed. To explain the obtained differences for pulsed laser and stationary thermal pretreatment, the effect of polymer heating rate on the features of chlorinated polyvinyl chloride decomposition was analyzed.
{"title":"Effects of Laser Pretreatment on the Formation of Nanostructured Carbon on the Surface of Chlorinated Polyvinyl Chloride under High-Power Ion Beam Irradiation","authors":"V. S. Kovivchak, S. A. Matyushenko","doi":"10.1134/s1027451024020071","DOIUrl":"https://doi.org/10.1134/s1027451024020071","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The features of formation of surface morphology of chlorinated polyvinyl chloride (pure and with the addition of the catalyst—ferrocene) under the influence of a high-power ion beam of nanosecond duration after the preliminary pulsed laser treatment of the polymer surface have been investigated. It was found that the morphology of the irradiated surface of chlorinated polyvinyl chloride after pulsed laser surface pretreatment differs significantly from the morphology of the irradiated surface of chlorinated polyvinyl chloride after preliminary stationary heat treatment. For pure chlorinated polyvinyl chloride, pulsed laser pretreatment with increasing power leads to an increase in the porosity of the surface layer after high-power ion beam irradiation, whereas different surface morphologies, including fibers (including polymer fibers) of different diameters, can be obtained for the pre-stationary thermal treatment of this polymer. Pre-stationary thermal pretreatment of chlorinated polyvinyl chloride with the addition of ferrocene (Fe(C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>) leads to a decrease in the diameter of the formed carbon nanofibers (with an increase in the treatment temperature). During the pulsed laser pretreatment, an increase in the porosity of the treated layer and a slight increase in the proportion of nanofibers of a larger diameter are observed. To explain the obtained differences for pulsed laser and stationary thermal pretreatment, the effect of polymer heating rate on the features of chlorinated polyvinyl chloride decomposition was analyzed.</p>","PeriodicalId":671,"journal":{"name":"Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140883698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-07DOI: 10.1134/s1027451024020149
E. G. Nikonov, R. G. Nazmitdinov, P. I. Glukhovtsev
Abstract
Quasi-two-dimensional systems play an important role in the manufacture of various devices for the needs of nanoelectronics. Obviously, the functional efficiency of such systems depends on their structure, which can change during phase transitions under the influence of external conditions (e.g., temperature). Until now, the main attention has been focused on the search for signals of phase transitions in continuous two-dimensional systems. One of the central issues is the analysis of conditions for the nucleation of the hexatic phase in such systems, which is accompanied by the appearance of defects in the Wigner crystalline phase at a certain temperature. However, both practical and fundamental questions arise about the critical number of electrons at which the symmetry of the crystal lattice in the system under consideration will begin to break and, consequently, the nucleation of defects will start. The dependences of the orientational order parameter and the correlation function, which characterize topological phase transitions, as functions of the number of particles at zero temperature have been studied. The calculation results allow us to establish the precursors of the phase transition from the hexagonal phase to the hexatic one for N = 92, 136, and 187 considered as an example.
摘要 准二维系统在制造满足纳米电子学需求的各种器件中发挥着重要作用。显然，这类系统的功能效率取决于其结构，而在相变过程中，结构会在外部条件（如温度）的影响下发生变化。迄今为止，人们的主要注意力都集中在寻找连续二维系统中的相变信号上。其中一个核心问题是分析此类体系中六方相成核的条件，在一定温度下，六方相会伴随着维格纳晶体相缺陷的出现。然而，在所考虑的体系中，临界电子数在多大程度上会开始破坏晶格的对称性，从而导致缺陷成核，这既是实际问题，也是基本问题。我们研究了零温度下表征拓扑相变的定向有序参数和相关函数与粒子数量的函数关系。以 N = 92、136 和 187 为例，通过计算结果，我们确定了从六方相到六方相的相变前兆。
{"title":"Manifestation of the Hexatic Phase in Confined Two-Dimensional Systems with Circular Symmetry","authors":"E. G. Nikonov, R. G. Nazmitdinov, P. I. Glukhovtsev","doi":"10.1134/s1027451024020149","DOIUrl":"https://doi.org/10.1134/s1027451024020149","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Quasi-two-dimensional systems play an important role in the manufacture of various devices for the needs of nanoelectronics. Obviously, the functional efficiency of such systems depends on their structure, which can change during phase transitions under the influence of external conditions (e.g., temperature). Until now, the main attention has been focused on the search for signals of phase transitions in continuous two-dimensional systems. One of the central issues is the analysis of conditions for the nucleation of the hexatic phase in such systems, which is accompanied by the appearance of defects in the Wigner crystalline phase at a certain temperature. However, both practical and fundamental questions arise about the critical number of electrons at which the symmetry of the crystal lattice in the system under consideration will begin to break and, consequently, the nucleation of defects will start. The dependences of the orientational order parameter and the correlation function, which characterize topological phase transitions, as functions of the number of particles at zero temperature have been studied. The calculation results allow us to establish the precursors of the phase transition from the hexagonal phase to the hexatic one for <i>N</i> = 92, 136, and 187 considered as an example.</p>","PeriodicalId":671,"journal":{"name":"Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140883555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-07DOI: 10.1134/s1027451024020356
T. V. Panova, V. S. Kovivchak
Abstract
The effect of a high-power ion beam of nanosecond duration on the phase composition and morphology of the surface of aluminum composite material SAP-2 is studied. It is found that after irradiation with a high-power ion beam under all irradiation modes used in the experiments no changes in the phase composition are observed. However, the observed shifts and broadening of the diffraction peaks from irradiated samples indicate the formation of residual stresses and transformation of the initial dislocation structure. The observed decrease in the dislocation density results in a decrease in the microhardness of SAP-2 irradiated at current densities of 50 and 100 A/cm2. It is shown that the increase in the ion-current density leads to an increase in the oxygen fraction in the surface layer of SAP-2, which is apparently associated with the partial evaporation of aluminum and an increase in the concentration of inclusions of Al2O3, which is part of the material. A nonlinear character of the dependence of the average ratio of the oxygen content to aluminum on the ion-current density of the beam is observed, the maximum value of which is recorded upon irradiation with a beam-current density of 100 A/cm2. Intense heating of the SAP-2 surface under ion-beam irradiation leads to changes in the dispersion of Al2O3 inclusions on the irradiated surface. The maximum coagulation of Al2O3 particles is found in the case of irradiation by a high-power ion beam with a current density of 100 A/cm2.
{"title":"Analysis of the State of the Surface Layer of the SAP-2 Composite Alloy after Irradiation with a High-Power Ion Beam","authors":"T. V. Panova, V. S. Kovivchak","doi":"10.1134/s1027451024020356","DOIUrl":"https://doi.org/10.1134/s1027451024020356","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The effect of a high-power ion beam of nanosecond duration on the phase composition and morphology of the surface of aluminum composite material SAP-2 is studied. It is found that after irradiation with a high-power ion beam under all irradiation modes used in the experiments no changes in the phase composition are observed. However, the observed shifts and broadening of the diffraction peaks from irradiated samples indicate the formation of residual stresses and transformation of the initial dislocation structure. The observed decrease in the dislocation density results in a decrease in the microhardness of SAP-2 irradiated at current densities of 50 and 100 A/cm<sup>2</sup>. It is shown that the increase in the ion-current density leads to an increase in the oxygen fraction in the surface layer of SAP-2, which is apparently associated with the partial evaporation of aluminum and an increase in the concentration of inclusions of Al<sub>2</sub>O<sub>3</sub>, which is part of the material. A nonlinear character of the dependence of the average ratio of the oxygen content to aluminum on the ion-current density of the beam is observed, the maximum value of which is recorded upon irradiation with a beam-current density of 100 A/cm<sup>2</sup>. Intense heating of the SAP-2 surface under ion-beam irradiation leads to changes in the dispersion of Al<sub>2</sub>O<sub>3</sub> inclusions on the irradiated surface. The maximum coagulation of Al<sub>2</sub>O<sub>3</sub> particles is found in the case of irradiation by a high-power ion beam with a current density of 100 A/cm<sup>2</sup>.</p>","PeriodicalId":671,"journal":{"name":"Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140883743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-07DOI: 10.1134/s1027451024020198
I. I. Tashlykova-Bushkevich
Abstract
The morphology, topography, and wettability with distilled water of Al–1.5 at % Fe alloy films with thicknesses of 25–90 nm are investigated. These films are formed on glass by ion-assisted deposition using a resonance ion source of vacuum arc plasma. Scanning probe microscopy reveals that the longitudinal and transverse roughness parameters, as well as dimensionless complexes, vary depending on the deposition mode and time. Measurement of these dimensionless parameters yields a quantitative description of cone formation processes in the Al–Fe/glass system. The mean roughness of the films increases in the range of 20–40 nm within the duration of deposition. Under self-irradiation conditions, the transition from island growth of the films to layered growth is observed. The effect of the substrate relief on the longitudinal step parameters of the film topography is found. Scanning electron microscopy is employed to examine the size and surface density of microdroplet-fraction particles. The size-frequency distributions of the microdroplet fraction are satisfactorily approximated by a lognormal distribution. Under self-ion irradiation conditions, 60–70% of particles comprising the microdroplet fraction are up to 0.8 µm in size. For the first time, a double Gaussian function is employed to approximate histograms of the distribution of relief features in the films, improving the accuracy in the description compared to a normal distribution law. The effectiveness of this approach in analyzing the structural formation of nanoscale films at various growth stages is demonstrated. By employing a bi-Gaussian model of the surface, the role of topographic characteristics in controlling the wetting of modified coatings is determined. The mechanism of the heterogeneous wetting of hydrophilic films in the Cassie state with contact edge angles of 50°–80° is discussed. In the potential mode, with an increase in deposition duration up to 10 h, the relief distribution of the films approximates a normal distribution, and the development of a submicrometer conical morphology on the surface leads to mixed wetting.
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