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Structure and hydrogen storage properties of the hexagonal Laves phase Sc(Al1-xNix)2
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.ORCID iD: 0000-0002-4752-5491
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2012 (English)In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 196, 132-137 p.Article in journal (Refereed) Published
Abstract [en]

The crystal structures of hydrogenated and unhydrogenated Sc(Al 1-xNi x) 2 Laves phases have been studied by combining several diffraction techniques and it is shown that hydrogen is situated interstitially in the A 2B 2-sites, which have the maximum number of scandium neighbours. The hydrogen absorption/desorption behaviour has also been investigated. It is shown that a solid solution of hydrogen forms in the mother compound. The hydrogen storage capacity exceeds 1.7 H/f.u. at 374 K, and the activation energy of hydrogen desorption was determined to 4.6 kJ/mol H 2. It is shown that these compounds share the same local coordination as Frank-Kasper-type approximants and quasicrystals, which opens up the possibility of finding many new hydride phases with these types of crystal structures.

Place, publisher, year, edition, pages
2012. Vol. 196, 132-137 p.
Keyword [en]
Hydrogen storage, Metal hydrides, X-ray diffraction, Approximants, Diffraction techniques, Hydrogen absorption, Hydrogen desorption, Hydrogen forms, Hydrogen storage capacities, Hydrogen storage properties, Laves phasis, Laves-phase, Local coordination, Mother compounds, New hydrides, Activation energy, Desorption, Hydrides, Hydrogen, X ray diffraction, Scandium
National Category
Chemical Sciences
URN: urn:nbn:se:uu:diva-184879DOI: 10.1016/j.jssc.2012.06.002ISI: 000310394500019OAI: oai:DiVA.org:uu-184879DiVA: diva2:570959
Available from: 2012-11-21 Created: 2012-11-15 Last updated: 2015-09-07
In thesis
1. Structural Basis for Hydrogen Interaction in Selected Metal Hydrides
Open this publication in new window or tab >>Structural Basis for Hydrogen Interaction in Selected Metal Hydrides
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Metal hydrides have existing and potential uses in many applications such as in batteries, for hydrogen storage and for heat storage. New metal hydrides and a better understanding of the behaviour of known metal hydrides may prove crucial in the realisation or further development of these applications. The aims of the work described in this thesis have been to characterise new metal hydrides, investigate how the properties of known metal hydrides can be improved and understand how their structure influences these properties. Metal hydrides, in most cases synthesised via high-temperature techniques, were structurally characterised using X-ray powder diffraction, X-ray single crystal diffraction and neutron powder diffraction and their thermodynamic and kinetic properties by in-situ X-ray powder diffraction, thermal desorption spectroscopy and pressure-composition-temperature measurements.

The investigations showed that: the storage capacity of the hexagonal Laves phase Sc(Al1-xNix)2 decreases with increasing Al content. There is a significant decrease in the stability of the hydrides and faster reaction kinetics when Zr content is increased in the cubic Laves phase Sc1-xZrx(Co1-xNix)2. Nb4M0.9Si1.1 (M=Co, Ni) form very stable interstitial hydrides which have very slow sorption kinetics. MgH2 mixed with 10 mol% ScH2 reaches full activation after only one cycle at 673 K while it takes at least four cycles at 593 K. LnGa (Ln=Nd, Gd) absorb hydrogen in two steps, it is very likely that the first step is interstitial solution of hydride ions into Ln4 tetrahedra and the second step places hydrogen atoms in Ln3Ga tetrahedra. The nature of the Ga-H bond is still unclear.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 74 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1234
National Category
Metallurgy and Metallic Materials Materials Chemistry Inorganic Chemistry
urn:nbn:se:uu:diva-245046 (URN)978-91-554-9187-1 (ISBN)
Public defence
2015-04-24, Häggsalen, Ångströmlaboratoriet Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Swedish Research Council
Available from: 2015-04-01 Created: 2015-02-24 Last updated: 2015-09-07

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Sahlberg, MartinÅngström, JonasPay Gómez, Ceasar
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