Synthesis and Crystal Structure of Sr<sub>2</sub>AlH<sub>7</sub>:  A New Structural Type of Alkaline Earth Aluminum Hydride

Zhang, Qing An; Nakamura, Yumiko; Oikawa, K.; Kamiyama, Takashi; Akiba, Etsuo

doi:10.1021/ic020450n

Cited by 50 publications

(36 citation statements)

References 17 publications

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“…As reported previously [1][2][3], SrAl 2 can be hydrogenated to SrAl 2 H 2 at about 463 K. Increasing the hydrogenation temperature to 513 K, SrAl 2 H 2 further absorbs hydrogen to form Sr 2 AlH 7 and Al. These reactions are shown below.…”

Section: Introductionsupporting

confidence: 77%

“…Therefore, SrAl 2 has been used as the starting material to synthesize Sr 2 AlH 7 [2]. However, the hydrogenation reaction rate is very slow because longrange diffusion of Al is necessary during the formation of Sr 2 AlH 7 .…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the Sr 2 AlH 7 hydride is always accompanied by Al in the product as shown in Eq. (2), which limits the yield of Sr 2 AlH 7 .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Synthesis of Sr2AlH7 by ball milling followed by hydrogenation

Zhang

Akiba

2005

Journal of Alloys and Compounds

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Section: Introductionsupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

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Synthesis of Sr2AlH7 by ball milling followed by hydrogenation

Zhang

Akiba

2005

Journal of Alloys and Compounds

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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].…”

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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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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