Synthesis of Sr2AlH7 by ball milling followed by hydrogenation

Zhang, Q.A.; Akiba, Etsuo

doi:10.1016/j.jallcom.2004.11.006

Cited by 14 publications

(15 citation statements)

References 12 publications

(18 reference statements)

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“…Using SrAl 2 as educt, the alloy can be hydrogenated to SrAl 2 H 2 at 463 K and to Sr 2 AlH 7 at 240 C [199][200][201]. Another possibility for the synthesis of Sr 2 AlH 7 is to ball mill Sr 2 Al alloy under hydrogen followed by additional hydrogenation [202,203]. Ball milling of Sr 2 Al under 0.6 MPa hydrogen for 10 h leads first to the formation of SrH 2 and Al.…”

Section: Sr 2 Alhmentioning

confidence: 99%

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Complex Hydrides

and

Felderhoff

2010

Handbook of Hydrogen Storage

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Complex hydrides are salt-like materials in which hydrogen is covalently bound to the central atoms, in this way a crystal structure consisting of so-called complex anions is formed. In general, complex hydrides have the chemical formula A x Me y H z . Compounds where position A is preferentially occupied by elements of the first and second groups of the periodic table and Me is occupied either by boron or aluminum are well known and have been intensively investigated. However, another possibility is that complex hydrides are built by transition metal cations. Complex metal hydrides have been known for more than 50 years, but for many years they were not considered for reversible hydrogen storage due to the high kinetic barriers of the decomposition requiring high temperatures. The situation changed in 1997 when Bogdanovi c and Schwickardi discovered that the kinetic barrier of the decomposition of the complex metal hydride, NaAlH 4 , can be lowered by the addition of Ti catalysts and that the material becomes reversible close to acceptable technical conditions [1]. They further showed not only that catalysts can enhance the kinetics of dehydrogenation but also that rehydrogenation under moderate conditions becomes feasible. This breakthrough induced the publication of a tremendous number of papers focusing on the synthesis and the properties of complex hydrides. The major goal is to understand the basic steps of dehydrogenation and rehydrogenation and the role of catalysts. Many complex metal hydrides have high hydrogen gravimetric storage capacities and some of them are commercially available. Some complex hydride systems, such as Mg 2 FeH 6 and Al(BH 4 ) 3 , have an extremely high volumetric hydrogen density of up to 150 kg m À3 . Compared to liquid hydrogen with a volumetric density of 70 kg m À3 , the amount of hydrogen in such metal hydrides is much higher. This makes complex transition metal hydrides interesting as potential storage materials.Handbook of Hydrogen Storage. Edited by Michael Hirscher

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Section: Sr 2 Alhmentioning

confidence: 99%

“…The monoclinic structure consists of isolated [AlH 6 ] 3À octahedra and of [HSr 4 ] 7 þ units. The [HSr 4 ] 7 þ tetrahedra are connected via shared edges and form infinite one-dimensional twisted chains [200,202]. The presence of [HSr 4 ] 7 þ units enables an easy rearrangement to SrH 2 during decomposition.…”

Section: Sr 2 Alhmentioning

confidence: 99%

Complex Hydrides

and

Felderhoff

2010

Handbook of Hydrogen Storage

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“…From the point of view of thermodynamics, SrH 2 can react with Al under hydrogen to form the hydride Sr 2 AlH 7 at 513-563 K [11][12][13][14]. However, Sr 2 AlH 7 cannot be obtained by hydrogenation of the ball milled 2SrH 2 + Al mixture but the ball milled Sr 2 Al alloy containing SrH 2 and Al at 533 K for 2 days.…”

Section: Formation Mechanism Of Sr 2 Alhmentioning

confidence: 99%

“…In our latest paper we reported that the Sr 2 AlH 7 hydride can be synthesized by ball milling of a Sr 2 Al alloy under hydrogen followed by further hydrogenation [14]. The as-cast Sr 2 Al alloy consisted of Sr 8 Al 7 , hexagonal Sr and fcc Sr phases.…”

Section: Introductionmentioning

confidence: 99%

Formation mechanism of Sr2AlH7

Zhang

Enoki

Akiba

2007

Journal of Alloys and Compounds

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“…Recently we reported that the Sr 2 AlH 7 hydride can be synthesized by ball milling of a Sr 2 Al alloy under hydrogen followed by further * Corresponding author. hydrogenation at 533 K [12]. The ball-milled product was the mixture of SrH 2 and Al.…”

Section: Introductionmentioning

confidence: 99%