Bulletin of the Russian Academy of Sciences: Physics最新文献

Theoretical and experimental studies were made of the flow of a thin layer of a magnetic fluid along a horizontal plane near an immobile magnetizable cylindrical body in an applied uniform vertical magnetic field. The shapes of the surface of the magnetic fluid at different times were constructed. The influence of the applied field on the flow of the layer was investigated.

The influence of gyromagnetic effects on magnetization of a magnetic fluid modeled as a suspension of spherical rigidly magnetized particles in a uniform magnetic field was theoretically investigated. An expression for the magnetization of the suspension was obtained. The parameter that determines the influence of the gyromagnetic effects was estimated.

Results are presented from studying the effect the magnitude of a magnetic field and the concentration of the magnetic phase of a magnetic fluid (MF) have on the coefficient of elongation and the shape of a drop of the MF floating in glycerol. Dependences are obtained for the MF droplet’s coefficient of elongation on the parameters of the magnetic fluids that are used and the strength of the magnetic field.

The authors study Raman scattering and FTIR absorption spectra of pure acetylacetone and aqueous solutions of it at room temperature and atmospheric pressure. Results from experiments and calculations show that a red shift of the C=O stretching vibrational band and a blue shift of the C–H stretching vibrational band are observed when the amount of acetylacetone in a solution is reduced. The distribution of potential energy is analyzed for the monomeric molecule of the keto form of acetylacetone. The calculated and observed frequencies of vibration are in good agreement. It is shown that acetylacetone creates molecular clusters with water molecules in the form of C=O…H and C–H…O hydrogen bonds, altering the shape of the spectral bands.

The authors study the orientational texturing of the magnetic moments of four magnetic nanoparticles fixed in the vertices of a regular tetrahedron and forming a separate multi-core particle. Monte Carlo calculations are used to obtain numerically the probability density of magnetic moment orientation, static magnetization, and the initial magnetic susceptibility of a multi-core particle.

A film of liquid helium on the surface of material traps for ultracold neutrons protects the neutrons from being absorbed by the trap walls. By using surface roughness and an electrostatic field, it is possible to maintain a helium film of sufficient thickness throughout the height of the trap. The field distribution near the tip of such wall roughness of the trap was calculated, and the effect of this field on holding the helium film was estimated.

The authors study compacted materials obtained using different periods of the mechanical activation of mixtures whose compositions correspond to alloys of grades VKNA-1V and VKNA-4U, with subsequent electric spark sintering. The maximum strengths of the compacted materials are reached after 3.5 min of mechanical activation: 1200 MPa for VKNA-1V and 1100 MPa for VKNA-4U.

An algorithm and original software are developed for obtaining and post-processing an experimental data array. The controlled pulsed heating of a probe is used to study the transfer of heat in liquid binary media and their phase diagrams, including the region of short-term superheated states. The Python program is tested by analyzing 1250 files containing more than 10⁷ values.

The temperature dependences of electrical conductivity and Hall coefficient in single crystals of bismuth and antimony tellurides were studied. In samples with a high content of antimony telluride, a decrease in Hall mobility in the range of liquid nitrogen temperatures was found, which indicates the presence of an additional mechanism for charge carrier scattering.

An investigation is performed of the effect produced by the technological parameters of a complex procedure for obtaining 3D printing powder of a new Nikalin aluminum alloy during dispersion in a ball mill, with the subsequent spheroidization of particles while processing the plasma.