(Sm1-xRx)2Fe17 (R = Ho, Er) alloys with х = 0.1, 0.2 and 0.4 were prepared by induction melting under inert gas atmosphere. The structure and magnetic hysteresis properties of both the initial compositions and hydrides based on them are investigated. It was found that (Sm1-xRx)2Fe17Нy hydrides like the parent compounds have a rhombohedral Th2Zn17-type of crystal structure (sp.gr. R m). Hydrogenation results in a significant increase in the Curie temperature and saturation magnetization at room temperature. Compositions with potentially high magnetic characteristics have been determined.

The composition, structure, topology of the surface of a cast, homogenized, and nitrogenated alloy based on the Sm2Fe17 intermetallic compound by Ho substitution for Sm have been investigated by means of X-ray fluorescence, X-ray diffraction, and scanning electron microscopy using BSE/EDS detectors. Magnetic properties are presented for initial Sm1.2Но0.8Fe17 compound, Sm1.2Но0.8Fe17N2.4 nitride and its milled powders. It has been established that the partial substitution of Sm by Ho in the rare-earth sublattice in combination with the effect of introduction of nitrogen into the lattice of initial compound lead to an increase of such magnetic characteristics as specific magnetization and coercive force. Comparative analysis of the magnetic hysteresis properties of powder samples showed that an increase of the milling time Sm-Ho-Fe-N powders using high-energy ball milling (15, 30, 45 and 60 min) improves the main magnetic characteristics. The functional characteristics of Sm-Ho-Fe-N powders prepared by milling are an important for the development of new high-coercive permanent magnets based on them.

Magnetocaloric properties of compounds Gd(Ni0.98Si0.02), Dy(Ni0.95Si0.05) and their hydrides Gd(Ni0.98Si0.02)H3, Dy(Ni0.95Si0.05)H4 were investigated in the temperature range 2 – 100K. It was found that partial substitution of Ni atoms by Si atoms, as well as subsequent hydrogenation can lead to a significant change in the Curie temperature (TC), the magnetocaloric effect, and the temperature at which the maximum MCE (Tmax) is observed. It is shown that the TC and Tmax of the hydrides are shifted by several degrees to the low temperature region with increasing or maintaining the MCE, which can significantly expand the application of such materials in cryogenic engineering.

The influence of hydrogen on the structure of thin cerium films formed by the method of magnetron sputter deposition was investigated in this work. Hydrogen-charging of the films was carried out by the method of Langmuir hydrogen dissociation on a tungsten substrate. The cerium hydride films were coated with a protective layer of nickel or chromium. It is demonstrated in this work that the used method of hydrogen charging can be used for introduction of hydrogen also into other hydride-forming metals and alloys.

In the present work, Mg–Ni–Mm alloys (where Mm is a mixture of rare earth metals) are studied to elaborate a chemical hydrogen source for portable energy systems based on fuel cells characterized by high gravimetric energy density used for unmanned air vehicles and robot systems. Hydrogen generation on demand by hydrolysis of metal hydrides (MgH2, Mg2NiH4) is proposed for the fuel cell power supply because it is the most efficient method characterized by high hydrogen storage density, safety, and low costs of the stored energy. The influence of the composition of alloys on the hydrogen absorption properties and hydrogen generation during hydrolysis is studied.

AbstractThe magnetic properties of intermetallic compounds GdNi_0.98Si_0.02 and DyNi_0.95Si_0.05 and hydrides based on them have been studied. It is found that a partial substitution of Si atoms for Ni atoms does not cause significant changes in the magnetic characteristics such as the Curie temperature. At the same time, incorporation of hydrogen into the crystal lattice of the GdNi_0.98Si_0.02 and DyNi_0.95Si_0.05 compounds leads to significant decrease in the Curie temperature, attenuation of exchange interactions due to significant increase in the unit cell volume (more than 20%), and an increase in the distances between magnetoactive ions. The magnetism of the initial and also hydrogenated compositions are mainly determined by the contribution from the subsystem of the rare-earth ions.

The magnetic properties of intermetallic compounds GdNi 0.98 Si 0.02 and DyNi 0.95 Si 0.05 and hydrides based on them have been studied. It is found that a partial substitution of Si atoms for Ni atoms does not cause significant changes in the magnetic characteristics such as the Curie temperature. At the same time, incorporation of hydrogen into the crystal lattice of the GdNi 0.98 Si 0.02 and DyNi 0.95 Si 0.05 compounds leads to significant decrease in the Curie temperature, attenuation of exchange interactions due to significant increase in the unit cell volume (more than 20%), and an increase in the distances between magnetoactive ions. The magnetism of the initial and also hydrogenated compositions are mainly determined by the contribution from the subsystem of the rare-earth ions.

The structure of deuterides based on V0.9Cr0.1 and V0.5Cr0.5 alloys has been investigated by neutron diffraction at room and low (77 K) temperatures. It is found that V0.9Cr0.1D2.0 deuteride has a CaF2 (Fm3m) crystal structure, which corresponds to vanadium dihydride. V0.5Cr0.5D0.7 deuteride has a NiAs (P6/3 mmc) structure type, similar to chromium hydride.