Влияние обработки высокоинтенсивным потоком ионов Zr на структуру и механические свойства высокопрочной стали 30ХГСН2А

Исследование структуры модифицированного поверхностного слоя высокопрочной стали30ХГСН2А проводили с помощью оптической просвечивающей электронной микроскопии, а так жеметодов рентгеновской дифракции. Испытания на статическое и циклическое растяжение проводилидля стальных образцов в состоянии поставки, а так же после модификации поверхностного слояпотоком ионов Zr

Influence of ion-beam treatment on structure and defor-mation resistance of 12Cr1MoV steel under static, cyclic and dynamic loading

Features of modification of structure and properties of 12Cr1MoV steel subjected to ion-beam irradiation by zirconium ion beam have been investigated with the use of optical and electron microscopy, and microhardness measurement. It was shown that after the treat-ment the modification occurs across the entire cross-section of specimens with the thickness of 1 mm. Changes in mechanical properties of these specimens under static, cyclic and impact loading were interpreted in terms of identified structure modifications

Structural levels of deformation and failure of heat-resistant 12Cr1MoV steel modified by vacuum arc treatment by Zr{+} ion beam

Study of structural changes occurring in the surface layer modified by ion-beam irradiation was carried out by means of optical, scanning and transmission electron microscopy. It was shown that irradiation induces the structure modification not only in the surface layer, but along the entire cross section of 1 mm thick specimens. It was elucidated that the complex pattern of structural changes is responsible for the pronounced variation of mechanical properties taking place under static tension and cyclic alternating bending

Sputtered NbN Films for Ultrahigh Performance Superconducting Nanowire Single-Photon Detectors

Nowadays ultrahigh performance superconducting nanowire single-photon detectors are the key elements in a variety of devices from biological research to quantum communications and computing. Accurate tuning of superconducting material properties is a powerful resource for fabricating single-photon detectors with a desired properties. Here, we report on the major theoretical relations between ultrathin niobium nitride (NbN) films properties and superconducting nanowire single-photon detectors characteristics, as well as ultrathin NbN films properties dependence on reactive magnetron sputtering recipes. Based on this study we formulate the exact requirements to ultrathin NbN films for ultrahigh performance superconducting nanowire single-photon detectors. Then, we experimentally study ultrathin NbN films properties (morphology, crystalline structure, critical temperature, sheet resistance) on silicon, sapphire, silicon dioxide and silicon nitride substrates sputtered with various recipes. We demonstrate ultrathin NbN films (obtained with more than 100 films deposition) with a wide range of critical temperature from 2.5 to 12.1 K and sheet resistance from 285 to 2000 ~$\Omega$/sq, as well as investigate a sheet resistance evolution over for more than 40\% within two years. Finally, we found out that one should use ultrathin NbN films with specific critical temperature near 9 K and sheet resistance of 400 ~$\Omega$/sq for ultrahigh performance SNSPD.Comment: The following article has been submitted to APL Materials. After it is published, it will be found at https://pubs.aip.org/aip/apm. Copyright 2023 Author(s). This article is distributed under a Creative Commons Attribution (CC BY) Licens

Origin of exchange bias in [Co/Pt]ML/Fe multilayer with orthogonal magnetic anisotropies

Magnetization reversal of soft ferromagnetic Fe layer, coupled to [Co/Pt]ML multilayer [ML] with perpendicular magnetic anisotropy (PMA), has been studied in-situ with an aim to understand the origin of exchange bias (EB) in orthogonal magnetic anisotropic systems. The interface remanant state of the ML is modified by magnetic field annealing, and the effect of the same on the soft Fe layer is monitored using the in-situ magneto-optical Kerr effect (MOKE). A considerable shift in the Fe layer hysteresis loop from the centre and an unusual increase in the coercivity, similar to exchange bias phenomena, is attributed to the exchange coupling at the [Co/Pt]ML and Fe interface. The effect of the coupling on spin orientation at the interface is further explored precisely by performing an isotope selective grazing incident nuclear resonance scattering (GINRS) technique. Here, the interface selectivity is achieved by introducing a 2 nm thick Fe57 marker between [Co/Pt]ML and Fe layers. Interface sensitivity is further enhanced by performing measurements under the x-ray standing wave conditions. The combined MOKE and GINRS analysis revealed the unidirectional pinning of the Fe layer due to the net in-plane magnetic spin at the interface caused by magnetic field annealing. Unidirectional exchange coupling or pinning at the interface, which may be due to the formation of asymmetrical closure domains, is found responsible for the origin of EB with an unusual increase in coercivity.Comment: 9 figures, 1 tabl

Rocking curve measurements revisited

The study of materials by diffraction methods started about 100 years ago with the pioneering experiment of Laue, Friedrich and Knipping, when the first X-ray diffraction patterns of single crystals were obtained (Friedrich et al., 1912). This was the beginning of a rapid development fostering many diffraction-based methods and techniques, which is still continuing. The measurement of rocking curves and the associated derived quantitative parameters, such as the ‘full width at half-maximum’ (FWHM) of the curves, has been performed since at least 1921 (Davis & Stempel, 1921) by exploiting the X-ray diffraction (XRD) properties of crystals. Since then, this has become one of the most powerful methods for the diffraction-based characterization of crystalline materials. The experimentally closely related method of X-ray diffraction imaging or X-ray diffraction topography has been used since about 1931 (Berg, 1931). Soon after World War II, the requirements of the electronics industry for the nondestructive analysis of defects in semiconductor materials like silicon and germanium (and others) boosted the improvement of these methods to their modern high-resolution variants like high-resolution X-ray diffraction and in particular high-resolution and high strain sensitivity X-ray topography (Bond & Andrus, 1952; Lang, 1957). This evolution was additionally accelerated in the late 1970s by the use of synchrotrons as dedicated X-ray sources and later on, starting in the 1990s, by the use of third-generation synchrotron sources...

Magnetic Dirac semimetal state of (Mn,Ge)Bi2_2Te4_4

For quantum electronics, the possibility to finely tune the properties of magnetic topological insulators (TIs) is a key issue. We studied solid solutions between two isostructural Z$_2$ TIs, magnetic MnBi$_2$Te$_4$ and nonmagnetic GeBi$_2$Te$_4$, with Z$_2$ invariants of 1;000 and 1;001, respectively. For high-quality, large mixed crystals of Ge$_x$Mn$_{1-x}$Bi$_2$Te$_4$, we observed linear x-dependent magnetic properties, composition-independent pairwise exchange interactions along with an easy magnetization axis. The bulk band gap gradually decreases to zero for $x$ from 0 to 0.4, before reopening for $x>0.6$, evidencing topological phase transitions (TPTs) between topologically nontrivial phases and the semimetal state. The TPTs are driven purely by the variation of orbital contributions. By tracing the x-dependent $6p$ contribution to the states near the fundamental gap, the effective spin-orbit coupling variation is extracted. As $x$ varies, the maximum of this contribution switches from the valence to the conduction band, thereby driving two TPTs. The gapless state observed at $x=0.42$ closely resembles a Dirac semimetal above the Neel temperature and shows a magnetic gap below, which is clearly visible in raw photoemission data. The observed behavior of the Ge$_x$Mn$_{1-x}$Bi$_2$Te$_4$ system thereby demonstrates an ability to precisely control topological and magnetic properties of TIs

Исторические аспекты математического анализа диаграмм деформации металлических материалов

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Energetic particle influence on the Earth's atmosphere

This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earth’s atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere