Study of the Hydrogen-Metal Systems

Hydrogen accumulation in samples of a palladium and 12Kh18N10T steel at the hydrogen charging by the electrolytic method and hydrogen release from these samples at its electron and X-ray irradiation are studied. Palladium was used as a comparison material (as most efficiently solvent hydrogen known among the simple materials). It is established that a capture effectiveness of hydrogen from an electrolyte (1 M H 2 SO 4 at current density is 0.5 A cm −2 ) for palladium is 3-4 orders more than for steel. The hydrogen yield nonlinearly increases with growing of electron current density and electron energy is more than 40 keV under electron irradiation of saturated palladium and 12Kh18N10T steel samples. About 90% of the hydrogen had removed from hydrogen saturated palladium samples and only 60% from steel under electron beam with energy 40 keV and current density ≈ 20 µA cm −2 for 1 h of irradiation. It is necessary to increase the energy of electrons from 40 to 100 keV for the more effective removal of hydrogen

The detailed studies of the structural and magnetic properties of hexaferrites Ba<inf>1−x</inf>Sr<inf>x</inf>Fe<inf>12</inf>O<inf>19</inf> for 0.0 ≤ x ≤ 0.75

The monophase polycrystalline hexaferrites Ba1−xSrxFe12O19 for 0 ≤ x ≤ 0.75 were prepared using the sol–gel synthesis method. The average crystallite size (Dac) ranged from 47 to 50 nm with Sr doping. The crystal structure and magnetic properties have been studied using X-ray diffraction (XRD) and neutron diffraction (ND). The structure of the studied hexaferrites is described by the hexagonal symmetry of P63/mmc space group. Field-emission scanning electron microscopy (FE-SEM) revealed the heterogeneous distribution of the grain sizes, which takes the hexagonal shape. Energy-dispersive X-ray spectroscopy (EDS) showed that the element compositions agree with the used components for each prepared sample. The substitution of Ba2+ ions by Sr2+ enhances the thermal stability of these hexaferrites. The magnetic hysteresis loops for the studied hexaferrite samples were obtained at room temperature. Different magnetic parameters are given in this work. The magnetocrystalline anisotropy parameter (Keff) initially increases for x ≤ 0.5 and then decreases for (x = 0.75). According to the analysis of neutron data, the magnetic structure formed by the Fe3+ ions, is located in five non-equivalent crystallographic sites with tetrahedral (Fe3-4f1), octahedral (Fe1-2a, Fe4-4f2, and Fe5-12k), and trigonal bipyramidal (Fe2-2b) coordinations. The strontium doping BaFe12O19 (BFO) hexaferrite affects the crystal lattice parameters, bond lengths, bond angles, and ordered magnetic moments of iron. Finally, the enhancement of the thermal stability and some magnetic parameters of the studied hexaferrite samples could be important for applications

Study of the Hydrogen-Metal Systems

Hydrogen accumulation in samples of a palladium and 12Kh18N10T steel at the hydrogen charging by the electrolytic method and hydrogen release from these samples at its electron and X-ray irradiation are studied. Palladium was used as a comparison material (as most efficiently solvent hydrogen known among the simple materials). It is established that a capture effectiveness of hydrogen from an electrolyte (1 M $H_2SO_4$ at current density is 0.5 A $cm^{-2}$) for palladium is 3-4 orders more than for steel. The hydrogen yield nonlinearly increases with growing of electron current density and electron energy is more than 40 keV under electron irradiation of saturated palladium and 12Kh18N10T steel samples. About 90% of the hydrogen had removed from hydrogen saturated palladium samples and only 60% from steel under electron beam with energy 40 keV and current density ≈ 20 μA $cm^{-2}$ for 1 h of irradiation. It is necessary to increase the energy of electrons from 40 to 100 keV for the more effective removal of hydrogen