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Hydrogen release and microstructure of MgH2 based composite powders containing a relevant amount of LaNi5

TitoloHydrogen release and microstructure of MgH2 based composite powders containing a relevant amount of LaNi5
Tipo di pubblicazioneArticolo su Rivista peer-reviewed
Anno di Pubblicazione2010
AutoriAbazović, N., Aurora A., Contini V., Mancini M.R., Montone Amelia, and M. Antisari Vittori
RivistaActa Physica Polonica A
Volume117
Paginazione841-848
ISSN05874246
Parole chiaveBall milling, Bulk diffusions, Composite micromechanics, Composite powders, Constant temperature, Decomposition kinetics, Gravimetric measurements, Hydrogen, Hydrogen release, Isothermal measurements, Lanthanum alloys, Microstructure, Optimum processing, Percolating networks, Phase transformation, Reaction kinetics, Reaction velocities, Reactive ball milling, Scanning electron microscopy, Second phase, Synthesis (chemical), Temperature scans, Thermoanalysis, Two phasis, Whole process, X ray diffraction, X ray diffraction analysis
Abstract

Micro-composite materials based on MgH2 with the addition of a relevant amount of LaNi5 have been synthesized by reactive ball milling. The powder microstructure has been studied by a combination of X-ray diffraction and scanning electron microscopy, while the decomposition behaviour and the hydrogen release properties have been obtained by differential thermal analysis and thermo-gravimetric measurements. Both temperature scans and constant temperature isotherms have been used to this purpose. Experimental results allow identifying optimum processing condition for synthesis of material that shows the onset of hydrogen release at temperatures as low as 450 K. The decomposition kinetics has been studied by isothermal measurements which show that the whole process cannot be described by just one mechanism limiting the reaction velocity. In fact in the first decomposition step the reaction is kinetically limited by the second phase nucleation, while, for partially decomposed samples the bulk diffusion appears to limit the process. On the basis of the experimental results we propose a mechanism of phase transformation where a percolating network of the two phases is formed.

Note

cited By 3

URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-77952719694&partnerID=40&md5=063630b6f86c6af6305ed5fde47d58a0
Citation KeyAbazović2010841