Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques最新文献

The paper presents the results of development and fabrication of X-ray microlenses from X-ray amorphous material, silica, by ion-beam lithography using modern systems combining a focused ion beam and a scanning electron microscope. The possibility of fabrication of glass microlenses with a concave parabolic profile and curvature radii from 2 to 30 μm and an aperture of 20 μm is demonstrated. A method for removing the redeposited layer using 5% hydrofluoric acid is tested. The achieved accuracy of parabolic microlens profile fabrication is less than 30 nm (minimum–maximum scatter), and the RMS roughness of the optical surface is less than 10 nm. The optical characteristics of silica microlenses for high-resolution X‑ray microscopy applications for new-generation synchrotron sources are evaluated.

Electrostatic ion sources with different methods of plasma excitation are widely used in the production of high-tech products, the surface modification of which provides predetermined properties. These properties essentially depend on the parameters of the generated ion beams, which are determined by the correspondence of the ion-extraction system to the required application, in particular, the optimal design of the ion source as a whole, including the working medium consumption parameters. This work is devoted to solving the problem of optimizing the flow rate of the ion source. It is proposed to consider the integral discharge parameters of a radio-frequency ion source operating as part of a vacuum process facility. This approach makes it possible to ignore the spatial distributions of discharge plasma parameters and to propose a simple model for determining the optimal coefficient of the source mass efficiency. An example of a calculation is shown, which allows a preliminary estimation of the parameters of the process facility.

The article presents the results of a study on the effect of ultrasonic exposure on the process of photocatalytic decomposition of metronidazole using ZnO microtetrapods under simultaneous irradiation with artificial sunlight. The synthesized zinc oxide microtetrapods had pronounced sharp tips, clear facets, and edges, indicating their high crystalline perfection. This unique morphology of ZnO microtetrapods provides the material with high catalytic activity in both photocatalytic and piezocatalytic processes. The Raman spectrum of ZnO microtetrapods showed distinct peaks corresponding to the transverse E₁ and high-frequency E_2h modes. The high intensity of the E_2h mode indicates the crystalline perfection of ZnO microtetrapods. The enhancement of the intensity of the transverse optical mode A₁ is observed at the tip of the tetrapod and is absent at its base. It has been shown that the use of ZnO microtetrapods allows significant efficiency in the decomposition of metronidazole due to the combined effect of light and ultrasound, creating a piezoelectric field on the surface of ZnO. This piezoelectric field promotes the spatial separation of photogenerated charges and reduces the likelihood of their recombination, significantly increasing the rate of decomposition of the target pollutant. The rate constant for the decomposition of metronidazole in piezo-photocatalysis is higher than the rate constants for photolysis, sonolysis, sonophotolysis, piezocatalysis, and photocatalysis by 1254, 35, 17, 8, and 4 times, respectively.

From last few years, transparent conducting oxide (TCOs) are gaining more attention in device technology. TCOs is an electrically conductive and optically transparent material. Its excellent properties have made it a promising material for various industries. Out of these TCOs, CdO is a binary compound of cadmium and oxygen, and has witnessed a dynamic evolution in its applications and understanding over the years. Cadmium Oxide (CdO) has garnered significant attention in scientific research and industrial applications due to its distinctive fundamental properties and versatile functionalities. Cadmium oxide is a prominent material, and it has wide applications like photovoltaic, optoelectronic, gas sensing, and solar cells when doped with different dopants. The objective of this review article is to deliver a wide-ranging understanding about CdO and its structural, optical, electrical properties and various applications, with the key directions of valuable resource for scientists, industry professionals, researchers operational in the fundamental properties and applications of this compound with a focus on its role in the semiconductor industry. Furthermore, this research article discussed the comparison analysis with cadmium telluride (CdTe) with the aim of elaborating the discussion concerning CdO. The evolution of CdO use might also be influenced by global perspectives on sustainability and environmental responsibility.

The microstructure and phase composition of Ti–6Al–4V/TiC metal matrix composite samples obtained by wire-feed electron-beam additive manufacturing are investigated by X-ray diffraction analysis and optical, scanning, and transmission electron microscopy. It is shown that the microstructure of the Ti–6Al–4V/TiC composite consists of primary β-grains containing α/α′-plates separated by interlayers of residual β- and α′′-phases. Irregularly shaped TiC carbide particles with sizes of 1–2 µm are distributed along the boundaries of the primary β-grains. The changes in the phase composition of the 3D-printed Ti–6Al–4V/TiC composites during heating from room temperature to 1100°C are investigated by X-ray diffraction using synchrotron radiation. The changes in the shape and position of the X-ray peaks of α/α′- and β-phases during heating and cooling are analyzed. It is shown that in the temperature range of 700–800°C, there is a shift of the 110 peak of the β-phase towards large angles, as well as a change in its full width at half maximum associated with the formation and subsequent decomposition of the orthorhombic α′′-phase.

The rapidly developing field of additive manufacturing requires quality control of finished products. In this regard, nondestructive testing methods, in particular X-ray computed microtomography, turned out to be in demand. The paper presents a study of the structure of the ZrO₂–20%Al₂O₃ ceramic composite obtained by the fused deposition modeling method of a thermoplastic suspension consisting of nanostructured powders of the same composition, a binder, and carbon nanotubes. To obtain information about the structure, two-dimensional sections of reconstructed images were analyzed. The anisotropy of the structure was shown, and possible causes of the heterogeneity of the pore and grain structure were explained. The information about the structure obtained by X-ray computed tomography will be used in further work to optimize the parameters of the fused deposition modeling technology and optimize the compositions of thermoplastic suspensions.

The spacecraft passive protection of monolithic and screen types has been considered. The screen passive protection includes an additional protective shield placed in front of the protected wall. The penetration length of particles for various types of passive protection has been estimated. Based on the simulation results and experimental data presented in the literature, the applicability ranges of various types of spacecraft passive protection are formulated.

A dynamic theory of coherent X-ray radiation generated by a beam of relativistic electrons in a composite target “amorphous layer-vacuum-periodic layered medium” has been developed. A periodic layered medium consists of three different layers arranged periodically, with the layers located at an arbitrary angle to the target surface. Coherent X-ray radiation exits through the rear surface of the target; that is, radiation in the periodic layered medium occurs in the Laue scattering geometry. Within the framework of the two-wave approximation of the dynamic theory of diffraction, expressions describing the spectral-angular densities of parametric X-ray radiation (PXR) in the periodic layered medium and diffracted transition radiation (DTR) are obtained and studied.

A method based on perturbation theory for describing ion–atom ionization collisions and an algorithm for statistical modeling of secondary electron trajectories are proposed for calculating the electron emission coefficient from a structureless solid target. The main contribution to the number of electrons emitted from the surface comes from electrons with energies E_e < 50 eV. Only a small target layer with a thickness of 20–40 Å determines the number of electrons emitted from the surface. If the target thickness exceeds this value, the electron emission coefficient does not depend on the target thickness. The change in the energy and charge of a fast ion in such a thin layer can be ignored, and the energy and charge of an ion emitted from the target can be used to estimate the number of secondary electrons.

The reflective and structural characteristics of a multilayer Ni(80)Mo(20)/C system, which is promising for the manufacture of Göbel mirrors and suppression of the CuK_β emission line (λ = 0.139 nm), have been studied for the first time. The optimal ratio of Ni(80)Mo(20) and C materials has been determined to achieve the best reflectivity at a wavelength of λ = 0.154 nm (CuK_α1 emission line). The reflection coefficient for periods d = 41.5 and 33.5 Å was R ≥ 69%. The positive effect of vacuum annealing of the Ni(80)Mo(20)/C structure, consisting in an increase in the first-order reflection coefficient, has been shown. The increase in reflectivity could be due to a decrease in the thickness of the transition regions and the “decompression” of the carbon layers, which is accompanied by an increase in the thickness of these layers, and an increase in the X-ray optical contrast at the interfaces. It has been found that vacuum annealing of the multilayer Ni(80)Mo(20)/C structure at temperatures up to 320°C does not significantly affect the distribution of local radiation grazing angles over the substrate area.