Mechanochemical transformations in Li(Na)AlH4-Li(Na)NH2 systems

Mechanochemical transformations of tetrahydroaluminates and amides of lithium and sodium have been investigated using gas volumetric analysis, X-ray powder diffraction, solid-state nuclear magnetic resonance (NMR) and transmission electron microscopy. In a transformation of LiAlH4 and LiNH2 taken in...

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Bibliographic Details
Published in:Acta materialia 2007-05, Vol.55 (9), p.3121-3130
Main Authors: DOLOTKO, Oleksandr, HAIQIAO ZHANG, UGURLU, Ozan, WIENCH, Jerzy W, PRUSKI, Marek, CHUMBLEY, L. Scott, PECHARSKY, Vitalij
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Metals. Metallurgy
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Summary:Mechanochemical transformations of tetrahydroaluminates and amides of lithium and sodium have been investigated using gas volumetric analysis, X-ray powder diffraction, solid-state nuclear magnetic resonance (NMR) and transmission electron microscopy. In a transformation of LiAlH4 and LiNH2 taken in an 1:1 molar ratio, the amount of released hydrogen (6.6wt.% after 30min ball milling) was higher than in any known one pot mechanochemical process involving a hydrogen-containing solid. A total of 4.3wt.% of hydrogen is released by the NaAlH4-NaNH2 system after 60min ball milling; and 5.2wt.% H2 is released when LiAlH4 and NaNH2 or NaAlH4 and LiNH2 are ball milled for 90min and 120min, respectively. All transformations proceed at room temperature. The mechanism of the overall transformation MAlH4(s)+MNH2(s)- > 2MH(s)+AlN(s)+2H2(g) was identified based on detailed spectroscopic analysis of the intermediate (M3AlH6) and final products of the ball milling process.
ISSN:1359-6454
1873-2453
DOI:10.1016/j.actamat.2007.01.016