The initial stages of Ge 1−x−y Si x Sn y film growth on Ge substrate were investigated and the kinetic diagram of the morphological state for GeSiSn films was built. The kinetic diagram for the GeSiSn films on the Ge substrate was compared to the kinetic diagram for GeSiSn films on Si substrate. New phase diagrams of the superstructural changes on the Sn surface were obtained at different initial conditions of the Sn cover deposition. The Sn film growth was performed at room temperature and 200 °C. Superstructures such as (7×1), (8×1) and (10×1) were first obtained on the Sn surface. The phase diagrams allow for determining and controlling the surface Sn cover during the multilayer periodical structures growth, as well as demonstrating the separate interest in obtaining the epitaxial thin Sn films. The multilayer structure growth with the pseudomorphic GeSiSn films on Ge and Si substrates was investigated using the phase diagrams for the superstructural changes of the Sn film and reflection high energy electron diffraction (RHEED) pattern. The rocking curves obtained by x-ray diffraction from the multilayer structures containing the GeSiSn layers with the Sn content up to 14% on the Ge and Si substrates demonstrate the pseudomorphic GeSiSn film state, sharp interfaces, as well as the conservation of the periodicity and content in all periods. The comparison of band diagrams based on Ge 1−x−y Si x Sn y /Si and Ge 1−x−y Si x Sn y /Ge heterostructures was performed, and the conditions, which correspond to the transition to the direct bandgap Ge 1−x−y Si x Sn y material, were determined. Based on the multilayer structures with the Ge 1−x−y Si x Sn y /Si heterojunction, p-i-n diodes were created and a vertical photocurrent was measured in the photovoltaic regime at zero bias. The p-i-n diode photocurrent extends at least to 4 μm.
The manufacture and study of the properties of magnetic materials requires the development of new automated devices for measuring their magnetic properties. To obtain nanosized materials with a pure phase, it is necessary to modernize former methods and develop new methods for synthesizing materials. As part of this study, a pulse magnetometer was made to study magnetic hysteresis loops. An exceptional feature of this device is the ability to conduct studies of the full cycle of the hysteresis loop using pulsed magnetic fields. M-type BaFe12O19 hexagonal ferrites were synthesized by standard ceramic, mechanochemical, and sol–gel methods. The structural, phase, and magnetic characteristics of the barium hexaferrites were studied. Methods for the synthesis of BaFe12O19 hexagonal ferrites were estimated and compared. Their structural and magnetic properties essentially depend on the method of synthesis. The mechanochemical technology makes it possible to obtain materials without impurity phases through the use of hydrated reagents in the synthesis. The use of sol–gel technology allows the synthesis to be carried out at much lower temperatures.
The paper presents the results of a study of the phase composition and the main static magnetic characteristics: saturation magnetization, residual magnetization and coercive force of polycrystalline ferroxplana type hexaferrites of the Ba2Ni2-xCuxFe12O22 (0 ≤ x ≤ 2.0) system. These materials have high magnetic permeability and are promising for use as substrates for magnetic antennas and radar absorbing materials. It is shown that thermograms of the initial permeability can be used to quickly assess the presence of impurity magnetic phases in complex oxide ferrimagnets. The permeability and permittivity spectra of textured and non-textured composite samples with the powder of the Ba2NiCuFe12O22 hexaferrite are measured in the microwave frequency range. The radar absorbing properties of the obtained composites are analyzed. It is shown that magnetic texturing leads to an increase in the operating frequency band of an absorber with RL < −10 dB from 6.1 GHz to 8.2 GHz and a deepening of the loss minimum from −21 dB to −27 dB.
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