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High hydrogen content super-lightweight intermetallics from the Li–Mg–Si system

Pavlyuk, Volodymyr and Dmytriv, Grygoriy and Chumak, Ihor and Gutfleisch, Oliver and Lindemann, Inge and Ehrenberg, Helmut (2013):
High hydrogen content super-lightweight intermetallics from the Li–Mg–Si system.
In: International Journal of Hydrogen Energy, Elsevier Science Publishing, pp. 5724-5737, 38, (14), ISSN 03603199,
[Online-Edition: http://dx.doi.org/10.1016/j.ijhydene.2013.02.078],
[Article]

Abstract

The existence of Li-rich super-lightweight intermetallics in the Li–Mg–Si ternary system has attracted attention for high capacity hydrogen storage materials. The hydrogenation properties of the alloys were studied by thermogravimetric analysis, differential scanning calorimetry in H2 atmosphere and X-ray diffraction. The Li-rich alloy absorbs the highest amount of hydrogen (8.8% w/w for Li70Mg10Si20), while the Mg-rich alloy (Li30Mg40Si30) absorbs 6.0% w/w H2 and shows the first experimental evidence for LiMgH3 formation with LiNbO3-type structure during hydrogenation.

The extension of homogeneity range of existing phases from Li–Mg–Si system was found and the crystal structures of four ternary phases, Li2+xMg1−xSi (x = 0.268), Li65−x+yMg30+x−ySi33 (x = 9.15, y = 1.23), Li7−x+yMg5+x−ySi4 (x = 1.14, y = 0.61) and Lix+yMg2−xSi (x = 0.51, y = 0.39), were solved and more precise refined using X-ray single crystal diffraction data. Electronic structure calculations reveal an increased occupation of electronic states at the Fermi level for Li12+xMg3−xSi4 in comparison to Li2+xMg1−xSi. The results of crystal orbital Hamilton population (COHP) and integrated crystal orbital Hamilton population (iCOHP) calculations for both structures indicate the strongest interactions between Mg–Si (-iCOHP = 1.999 eV) and the weakest between Li–Li (-iCOHP = 0.049 eV).

Item Type: Article
Erschienen: 2013
Creators: Pavlyuk, Volodymyr and Dmytriv, Grygoriy and Chumak, Ihor and Gutfleisch, Oliver and Lindemann, Inge and Ehrenberg, Helmut
Title: High hydrogen content super-lightweight intermetallics from the Li–Mg–Si system
Language: English
Abstract:

The existence of Li-rich super-lightweight intermetallics in the Li–Mg–Si ternary system has attracted attention for high capacity hydrogen storage materials. The hydrogenation properties of the alloys were studied by thermogravimetric analysis, differential scanning calorimetry in H2 atmosphere and X-ray diffraction. The Li-rich alloy absorbs the highest amount of hydrogen (8.8% w/w for Li70Mg10Si20), while the Mg-rich alloy (Li30Mg40Si30) absorbs 6.0% w/w H2 and shows the first experimental evidence for LiMgH3 formation with LiNbO3-type structure during hydrogenation.

The extension of homogeneity range of existing phases from Li–Mg–Si system was found and the crystal structures of four ternary phases, Li2+xMg1−xSi (x = 0.268), Li65−x+yMg30+x−ySi33 (x = 9.15, y = 1.23), Li7−x+yMg5+x−ySi4 (x = 1.14, y = 0.61) and Lix+yMg2−xSi (x = 0.51, y = 0.39), were solved and more precise refined using X-ray single crystal diffraction data. Electronic structure calculations reveal an increased occupation of electronic states at the Fermi level for Li12+xMg3−xSi4 in comparison to Li2+xMg1−xSi. The results of crystal orbital Hamilton population (COHP) and integrated crystal orbital Hamilton population (iCOHP) calculations for both structures indicate the strongest interactions between Mg–Si (-iCOHP = 1.999 eV) and the weakest between Li–Li (-iCOHP = 0.049 eV).

Journal or Publication Title: International Journal of Hydrogen Energy
Volume: 38
Number: 14
Publisher: Elsevier Science Publishing
Uncontrolled Keywords: Hydrogen-storage alloys, Lithium alloys, Crystal structure, Hydrogenation
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Functional Materials
11 Department of Materials and Earth Sciences > Material Science > Structure Research
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 06 Jun 2013 08:26
Official URL: http://dx.doi.org/10.1016/j.ijhydene.2013.02.078
Identification Number: doi:10.1016/j.ijhydene.2013.02.078
Funders: Financial support from the Deutsche Forschungsgemeinschaft (DFG, EH183/7), the Ministry of Education and Science of Ukraine (M/206–2009) and the Bundesministerium für Bildung und Forschung (WTZ UKR 08/024) is gratefully acknowledged., Authors are grateful to the European Union (ERDF) as well as the Free State of Saxony (SAB grant-no. 100112628).
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