Structure and hydrogen storage properties of the hexagonal Laves phase Sc(Al1-xNix)2

• 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.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

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

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