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Role of additives in LiBH4–MgH2 reactive hydride composites for sorption kinetics / U. Bösenberg in Acta materialia, Vol. 58 N° 9 (Mai 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 9 (Mai 2010) . - pp. 3381–3389 Titre : Role of additives in LiBH4–MgH2 reactive hydride composites for sorption kinetics Type de document : texte imprimé Auteurs : U. Bösenberg, Auteur ; J.W. Kim, Auteur ; D. Gosslar, Auteur Année de publication : 2011 Article en page(s) : pp. 3381–3389 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Hydrogen  storage  Nanocomposites  Heterogeneous  nucleation  of  phase  transformations  Phase  transformation  kinetics Résumé : The influence of additives on the reaction kinetics and microstructure refinement in LiBH4–MgH2 composites is investigated in detail. Indications of the rate-limiting processes during the reactions are obtained by comparison of the measured reaction kinetics with simulations with one specific rate-limiting process. The kinetics of the sorption reactions are derived from volumetric measurements as well as from in situ X-ray diffraction measurements. During desorption, the hydrogen is released at a constant rate, which is possibly correlated with the one-dimensional growth of MgB2 platelets. In contrast, the kinetic curves of the absorption reactions exhibit the typical shape of contracting-volume controlled kinetics. The microscopical interpretation of kinetic measurements are supported by transmission electron microscopy images confirming the formation of additive-nanostructures in the grain boundaries upon cycling. The present investigations underline the importance of the additives as nucleation substrates and the influence of microstructure on the reaction kinetics. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000984 [article] Role of additives in LiBH4–MgH2 reactive hydride composites for sorption kinetics [texte imprimé] / U. Bösenberg, Auteur ; J.W. Kim, Auteur ; D. Gosslar, Auteur . - 2011 . - pp. 3381–3389. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 9 (Mai 2010) . - pp. 3381–3389 Mots-clés : Hydrogen  storage  Nanocomposites  Heterogeneous  nucleation  of  phase  transformations  Phase  transformation  kinetics Résumé : The influence of additives on the reaction kinetics and microstructure refinement in LiBH4–MgH2 composites is investigated in detail. Indications of the rate-limiting processes during the reactions are obtained by comparison of the measured reaction kinetics with simulations with one specific rate-limiting process. The kinetics of the sorption reactions are derived from volumetric measurements as well as from in situ X-ray diffraction measurements. During desorption, the hydrogen is released at a constant rate, which is possibly correlated with the one-dimensional growth of MgB2 platelets. In contrast, the kinetic curves of the absorption reactions exhibit the typical shape of contracting-volume controlled kinetics. The microscopical interpretation of kinetic measurements are supported by transmission electron microscopy images confirming the formation of additive-nanostructures in the grain boundaries upon cycling. The present investigations underline the importance of the additives as nucleation substrates and the influence of microstructure on the reaction kinetics. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000984