Use of Neutron Diffraction for the Development of Metal Hydrides for Hydrogen Storage

Abstract

Metal hydrides are attractive solutions for hydrogen storage in a wide range of applications going from fuel cell submarine down to smart phones. In metal hydrides hydrogen is chemically bonded to other elements to form an alloy. Therefore, knowledge of the crystal structure of the metal hydride in its hydride and dehydrided state is essential. However, as hydrogen is difficult to be localized from X-ray diffraction, neutron diffraction is basically the only waynon- destructively evaluate the crystal structures of metal hydrides. In this paper we will present the use of neutron diffraction in two different metal hydrides systems. First, we will show that from neutron diffraction we were able to demonstrate the relationship between the metastable orthorhombic γ-MgH2 and the tetragonal β-MgH2. The second example is the two phase compound TiV0.9Mn1.1 in which the exact elemental composition and localization of the atoms in the crystal structures could only be achieved from neutron diffraction.We will end this talk with a general discussion on the benefit of using neutron techniques for the development of metal hydrides.