Search academic texts

Information × Registration Number 0203U006565, 0100U004870 , R & D reports Title Development of novel metal hydride technologies for control of structure and properties of high-performance materials for permanent magnets and electrochemical power sources popup.stage_title Head Fedorov V.V., Registration Date 12-06-2003 Organization Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine popup.description2 Objects of studies: metal hydride materials based on alloys of rare earth metals and zirconium and technological processes of their treatment in hydrogen. The aim of the work: to perform a complex studies of hydrogen absorption capacity, kinetics of phase transition and physicochemical properties of intermetallic compounds of Zr and rare earth metals (RE) for determination of principal regularities of the effect of their treatment in hydrogen on phase-structural state. To create on this base recommendations for hydrogen technology of the control of magnetic and electrochemical characteristics of metal hydrides. Methods of studies: differential thermal analysis in hydrogen; hydrogenation under pressure up to 100 bar and temperatures up to 990°C; thermal desorption spectroscopy, measurements of isotherms (Sieverts method); neutron diffraction analysis, precision synchrotron X-ray analysis; magnetic measurements (Moess-Bauer spectroscopy, magnetization); measurements of charge-discharge characteristics ofmetal hydride electrode. Principal results: The oxygen modification of intermetallic hydrogen absorbers on the basis of Zr and Ti was found to allow the controlled changes in their physicochemical properties (thermal stability, stability toward disproportionation, hydrogen absorption and electrochemical discharge capacity). It has been shown for the first time that hydrogen atoms effect the diffusion redistribution of oxygen atoms in interstices of crystal lattice. The neutron diffraction analysis allowed finding uniquely short H-H distances in metal hydrides of RE-Ni-In system, which gave the ground for reassessment of the classical "rule of 2A" of the structural chemistry of metal hydrides. Materials of this type were shown to be the basis for the creation of new high-efficiency hydrogen storage materials. The HDDR method was proposed for the homogenization of metal hydride materials on the basis of RE and Zr, which allows obtaining materials with even structure, excluding the stage of isothermal annealingat 873-1273 К. It has been shown for the first time that the HDDR processing of materials for negative metal hydride electrodes improves their charge-discharge characteristics and cyclic stability. The temperature-time condition for the HDDR processing of industrial magnetic alloys Dd-Fe-B and Sm-Co have been identified, phase composition of disproportionation products and their crystallography characteristics were determined, the dependence of changes of critical temperature of disproportionation on the concentration of inserted hydrogen has been observed for the first time. Product Description popup.authors popup.nrat_date 2020-04-02 Close