Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1623949 | Journal of Alloys and Compounds | 2008 | 5 Pages |
Solid aluminum hydride, AlH3, has been proposed and studied for applications in hydrogen storage. In some samples, a comparatively narrow feature in the proton NMR spectrum is observed; we demonstrate here that this peak is due to molecular hydrogen (H2) trapped within the solid, presumably from earlier processing procedures or partial decomposition. Static and magic-angle spinning NMR show that the responsible species is highly mobile, even at 11 K. Neutron-energy-gain spectra obtained at 3.5 K yield a feature at or near the free-rotor H2 energy difference between the J = 1 and J = 0 states. Both NMR and neutron scattering demonstrate ortho–para conversion at low temperatures. Similar NMR signatures in other hydrogen-storage solids such as NaAlH4 may also be due to trapped H2.