1. Role of additives in LiBH4–MgH2 reactive hydride composites for sorption kinetics
- Author
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Bösenberg, U., Kim, J.W., Gosslar, D., Eigen, N., Jensen, T.R., von Colbe, J.M. Bellosta, Zhou, Y., Dahms, M., Kim, D.H., Günther, R., Cho, Y.W., Oh, K.H., Klassen, T., Bormann, R., and Dornheim, M.
- Subjects
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NANOCOMPOSITE materials , *HYDRIDES , *CHEMICAL kinetics , *ABSORPTION , *MICROSTRUCTURE , *PHASE transitions , *SIMULATION methods & models , *X-ray diffraction - Abstract
Abstract: 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. [Copyright &y& Elsevier]
- Published
- 2010
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