title: Evidence of the hydrogen release mechanism in bulk MgH2.
abstract: Hydrogen has the potential to power much of the modern world with only water as a by-product, but storing hydrogen safely and efficiently in solid form such as magnesium hydride remains a major obstacle. A significant challenge has been the difficulty of proving the hydriding/dehydriding mechanisms and, therefore, the mechanisms have long been the subject of debate. Here we use in situ ultra-high voltage transmission electron microscopy (TEM) to directly verify the mechanisms of the hydride decomposition of bulk MgH2 in Mg-Ni alloys. We find that the hydrogen release mechanism from bulk (2 μm) MgH2 particles is based on the growth of multiple pre-existing Mg crystallites within the MgH2 matrix, present due to the difficulty of fully transforming all Mg during a hydrogenation cycle whereas, in thin samples analogous to nano-powders, dehydriding occurs by a 'shrinking core' mechanism.
authors: 1] Nihon Superior Centre for the Manufacture of Electronic Materials, School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia [2] Department of Applied Quantum Physics and Nuclear Engineering and the Ultramicroscopy Research Center, Kyushu University, Fukuoka 819-0395, Japan.
authors: Kazuhiro
authors: K
authors: Nogita
authors: Nihon Superior Centre for the Manufacture of Electronic Materials, School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia.
authors: Xuan Q
authors: XQ
authors: Tran
authors: Department of Applied Quantum Physics and Nuclear Engineering and the Ultramicroscopy Research Center, Kyushu University, Fukuoka 819-0395, Japan.
authors: Tomokazu
authors: T
authors: Yamamoto
authors: Department of Applied Quantum Physics and Nuclear Engineering and the Ultramicroscopy Research Center, Kyushu University, Fukuoka 819-0395, Japan.
authors: Eishi
authors: E
authors: Tanaka
authors: Nihon Superior Centre for the Manufacture of Electronic Materials, School of Mechanical and Mining Engineering, The University of Queensland, Brisbane, QLD 4072, Australia.
authors: Stuart D
authors: SD
authors: McDonald
authors: Department of Materials, Imperial College, London. SW7 2AZ. UK.
authors: Christopher M
authors: CM
authors: Gourlay
authors: Department of Applied Quantum Physics and Nuclear Engineering and the Ultramicroscopy Research Center, Kyushu University, Fukuoka 819-0395, Japan.
authors: Kazuhiro
authors: K
authors: Yasuda
authors: Department of Applied Quantum Physics and Nuclear Engineering and the Ultramicroscopy Research Center, Kyushu University, Fukuoka 819-0395, Japan.
authors: Syo
authors: S
authors: Matsumura