Multisubstituted barium ferrites with a magnetoplumbite structure were obtained by the method of solid-phase reactions with ferritization and pre-firing. Three-charged, mainly diamagnetic cations Al3+, Cr3+, Ga3+, and In3+ were chosen as substituents for the Fe3+ iron cations, the proportion of which in solid solutions did not exceed 50%. The values of the configurational mixing entropy were calculated for all the compositions. A slight deviation of the chemical composition of the obtained solid solutions from the nominal value was established by the energy-dispersive X-ray spectroscopy method. The phase purity and values of the unit cell parameters were refined from X-ray scattering data using full-profile analysis in the Rietveld method. A non-monotonic behavior of the unit cell parameters as a function of the B-sub-lattice average ionic radius of the magnetoplumbite structure was found. A minimum unit cell volume of ~667.15 Å3 was found for the composition BaFe6.11Al1.56Cr2.17Ga2.16O19 with a B-sub-lattice average ionic radius of ~7.449 Å. The average crystallite size varied within 5.5–6.5 μm. The temperature and field dependencies of the magnetization have been measured. The values of the saturation magnetization, residual magnetization, hysteresis loop squareness, and coercivity at 50 K and 300 K were extracted from the experimental data. Using the Law of Approach to Saturation, the magnetic crystallographic anisotropy coefficient and anisotropy field were calculated. Multisubstitution leads to a significant decrease in such magnetic parameters as the magnetic ordering temperature and spontaneous magnetization at both temperatures. The maximum magnetic ordering temperature of ~297.7 K was found for the composition BaFe5.84Ga6.19O19 with a B-sub-lattice average ionic radius of ~7.586 Å in a field of 500 Oe. A maximum saturation magnetization of ~24.7 emu/g was found for the composition BaFe5.84Ga6.19O19 with a B-sub-lattice average ionic radius of ~7.586 Å at 50 K. A maximum hysteresis loop squareness of ~0.72 was found for the composition BaFe6.11Al1.56Cr2.17Ga2.16O19 with an average ionic radius of ~7.449 Å at 50 K. A maximum magnetic crystallographic anisotropy coefficient of ~2.09 × 105 Erg/g was found for the composition BaFe6.19Al1.25Cr1.57Ga1.74In1.26O19 with a B-sub-lattice average ionic radius of ~7.706 Å at 50 K. The frustrated magnetic state including the nano-sized clusters with an average diameter in the range of 50–200 nm was established from the results of measuring the ZFC and FC temperature magnetizations. The interpretation of the obtained experimental data is carried out taking into account the increased stability of high-entropy phases and regular changes in the intensity of the Fe3+(Al3+, Cr3+, Ga3+, In3+)–O2−–Fe3+(Al3+, Cr3+, Ga3+, In3+) indirect superexchange interactions as a result of magnetic dilution of the iron sub-lattice in the magnetoplumbite structure.

This paper presents the brief review of Chelyabinsk group of meteoroid, bolide and meteorite "Chelyabinsk" investigations. Height of the maximum of the main flash of Chelyabinsk bolide is 30 km. Only 1% of meteoroid mass arrived to the Earth surface in the form of meteorites while the most part of meteoroid became dust. During four days the dust had circumnavigated the globe and formed stratospheric dust belt. This new dust belt, located above the Junge aerosol layer, has persisted over at least a three-month period. The mass distribution of found meteorites is lognormal. This shape argues that fragmentation process of initial body happened randomly and in a cascade way. Transparent or translucent mineral filaments firmly linked to the particles were found in the meteoritic dust. In metallic phases of the meteorite mainly Fe-rich compounds exist. Very interesting topics of next research are magnetic properties of Fe-Ni phase, because of cosmic synthesis conditions. Meteoroids like "Chelyabinsk" fall on average once every 30 years. Therefore the problem of "asteroid and comet danger" should be expanded to the problem of "meteoroid, asteroid and comet danger".

The results of direct measurements of the magnetic field induced entropy change in the Ni _{2.19} Mn _{0.81} Ga alloy are presented. It is shown that the largest entropy change in the magnetic field 2.6 T is equal to 11 J/kgK. The experimental data are compared with the theoretical results, obtained with the help of the statistical and molecular field theory.

Thrombosis-related diseases are the primary cause of death in the world. Despite recent advances in thrombosis treatment methods, their invasive nature remains a crucial factor, which leads to considerable deadly consequences. Soft magnetic robots are attracting widespread interest due to their fast response, remote actuation, and shape reprogrammability and can potentially avoid the side effects of conventional approaches. This paper outlines a new approach to the thrombosis treatment via reprogrammable magnetic soft robots that penetrate, hook, and extract the plasma clots in a vein-mimicking system under applied rotating magnetic fields. We present shape-switching bioinspired soft swimmers, capable of locomotion by different mechanisms in vein-mimicking flow conditions and whose swimming efficiency is similar to animals. Further, we demonstrate the potential of a developed robot for minimally invasive thromboextraction with and without fibrinolytic usage, including hooking the plasma clot for 3.1 ± 1.1 min and extracting it from the vein-mimicking system under the applied magnetic fields. We consider an interesting solution for thrombosis treatment to avoid substantial drawbacks of the existing methods.

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