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The defect structure of α -phase gallium oxide thin films was investigated using transmission electron microscopy (TEM). Epitaxial Ga2O3 films were grown via halide vapor-phase epitaxy on c -plane sapphire substrates. TEM analysis revealed a high density of extended planar defects within the films, primarily located along prismatic planes of { 11 2 ¯ 0 } type. Displacement vectors were determined using the invisibility criterion for stacking faults. The study encompassed both planar and cross-sectional views of the films. It is hypothesized that these defects form due to the motion of edge partial dislocations with the 1 3 ⟨ 1 1 ¯ 00 ⟩ Burgers vector. Various mechanisms of their formation have been explored. [ABSTRACT FROM AUTHOR]

The Landau states of electrons with orbital angular momentum in magnetic fields are important in the quantum theories of metals and of synchrotron radiation at storage rings, in relativistic astrophysics of neutron stars, and in many other areas. In realistic scenarios, electrons are often born inside the field or injected from a field-free region, requiring nonstationary quantum states to account for boundary or initial conditions. This study presents nonstationary Laguerre–Gaussian (NSLG) states in a longitudinal magnetic field, characterizing vortex electrons after their transfer from vacuum to the field. Comparisons with Landau states and calculations of observables such as mean energy and root-mean-square (r.m.s.) radius show that the r.m.s. radius of the electron packet in the NSLG state oscillates in time around a significantly larger value than that of the Landau state. This quantum effect of oscillations is due to boundary conditions and can potentially be observed in various problems, particularly when using magnetic lenses of electron microscopes and linear accelerators. Analogies are drawn between a quantum wave packet and a classical beam of many particles in phase space, including the calculation of mean emittance of the NSLG state as a measure of its quantum nature. [ABSTRACT FROM AUTHOR]

γ'Ni3Al-based casting alloys have a lower density, higher melting point and resistance to oxidation, and a higher ceiling of operating temperatures than modern heat-resistant nickel alloys. The article discusses the features of the electronic structure and crystallization of domestic (such as VKNA/VIN) and the most advanced foreign (γ' + γ) low-alloyed γ'Ni3Al-based alloys (IC type), and experimental data on the nature of the structures formed during directional crystallization of alloys with different types of alloying and on the nature of the distribution of components in the γ'Ni3Al and γNi phases and structural components in the cellular-dendritic structure of single crystals with 〈111〉 and 〈001〉 crystallographic orientation are presented. The influence of heat treatment on the microstructure, distribution of alloying elements, and mechanical properties of the VKNA type alloys is investigated in a wide range of temperature–time parameters. A comparative analysis of the effect of temperature and duration of heat treatment and cooling rate after heat treatment on the heat resistance of alloys showed that, unlike other Ni3Al-based alloys, for single crystals from the VKNA type economically alloyed alloys and parts made from them (uncooled working blades of aviation gas turbine engines, nozzle apparatuses, jet nozzle spacers, and other parts of the hot path of gas turbine engines), a short-term heat treatment (1150°C/1 h) is necessary and sufficient to relieve casting stresses. The alloys demonstrate high heat resistance at 1100–1200°C and the ability to withstand short-term casting temperatures up to 1250–1300°C. [ABSTRACT FROM AUTHOR]

The results of a study by transmission electron microscopy of the structural state of α-Ga2O3 film with a thickness of about 1 micron, grown on the prismatic m-face sapphire by the method of chloride vapor phase epitaxy, are presented. The influence of the substrate orientation on the formation of the dislocation structure is discussed. Threading dislocations, including those with the Burgers vector 1/3(), and dislocation half-loops are revealed. The inclined propagation of dislocations and the of the threading dislocation density near the surface. [ABSTRACT FROM AUTHOR]

The spatial spin modulated structure (SSMS) of the cycloid type present in bulk BiFeO3 prevents the linear magnetoelectric effect. One way to influence this structure is to reduce the crystal size to the nanoscale. Various opinions are circulating in the literature about the effect of nanocrystal size on SSMS, and to investigate this issue, we used a number of methods, with zero-field NMR (ZF NMR) spectroscopy at the forefront. ZF NMR spectroscopy enables the direct observation of the distribution profile of local fields on iron atoms and defines the SSMS presence and its properties. We also examined the synthesized samples using XRD, TEM, and magnetometry. We conclude that SSMS persists as the nanocrystal size decreases to the cycloid period and less, becoming more harmonic. This is accompanied by the change of the anisotropy type from an "easy axis" to an "easy plane". Magnetic measurements show a significant increase in the saturation magnetization, remanent magnetization, coercivity, and exchange bias of nanocrystals with sizes close to the cycloid period, which is probably associated with incomplete spin compensation in the case of an incomplete cycloid period. Despite the fact that SSMS is retained in the samples with decreased size, the magnetic properties experience a sharp increase up to applicable values. [ABSTRACT FROM AUTHOR]

Vibrations and waves are investigated in periodic systems that consist of identical subsystems having an arbitrary structure. Spectral regularities are found for such systems. Their dispersion curves are shown to consist of branches, each of which corresponds to its own mode shape of elastic vibrations of the subsystem. The presence of band gaps in such systems, in which a harmonic signal cannot be transmitted, was revealed, and their boundaries were determined. The mode shapes of vibrations in various frequency ranges are obtained. Modulated waves are shown to arise in the system due to modulation by lower frequencies, which correspond to system vibrations without taking into account the elastic properties of the constituent subsystems. [ABSTRACT FROM AUTHOR]