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Type: Artigo de periódico
Title: Synthesis and hydrogen sorption properties of Mg2FeH6-MgH2 nanocomposite prepared by reactive milling
Author: Asselli, AAC
Leiva, DR
Jorge, AM
Ishikawa, TT
Botta, WJ
Abstract: The complex hydride Mg2FeH6 is an interesting material for hydrogen storage due to its high gravimetric hydrogen capacity as well as for having the highest known volumetric hydrogen density - 150 kg m(-3). Several papers have recently reported its synthesis from the stoichiometric precursors 2Mg-Fe or 2MgH(2)-Fe through sintering process and ball milling under argon or hydrogen atmosphere. However, regardless of processing conditions, a remaining iron always was identified by X-rays diffraction, which resulted in a lower hydrogen storage capacity. In the present paper, the Mg2FeH6-MgH2 nanocomposite was successfully synthesized through high-energy ball milling from 3Mg-Fe mixture under hydrogen atmosphere at room temperature. After the ball milling, X-rays diffraction patterns showed that the iron was kept to a minimum, which was also confirmed by simultaneous thermal analysis of differential scanning calorimetry and thermogravimetry. The gravimetric density of the ball milled 3Mg-Fe is more than 5 wt.% of hydrogen. In the case of 2Mg-Fe, processed in the same condition, the measured hydrogen capacity was 3.5 wt.%. The hydrogen sorption kinetics analyses were performed in a Sievert's apparatus in temperatures ranging from 250 degrees C to 350 degrees C. Enhanced hydrogen sorption kinetics was observed for these 3Mg-Fe milled powders in comparison with the 2Mg-Fe ones. (c) 2012 Elsevier B.V. All rights reserved.
Subject: Metal hydrides
Nanostructured materials
Mechanochemical processing
Hydrogen storage
Country: Suíça
Editor: Elsevier Science Sa
Rights: fechado
Identifier DOI: 10.1016/j.jallcom.2011.12.103
Date Issue: 2012
Appears in Collections:Unicamp - Artigos e Outros Documentos

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