This review focuses on key aspects of the thermal decomposition of multinary or mixed hydride materials, with a particular emphasis on the rational control and chemical tuning of the strategically important thermal decomposition temperature of such hydrides, Tdec. An attempt is also made to predict the thermal stability of as-yet unknown, elusive or even unknown hydrides. The future of a particularly promising class of materials for hydrogen storage, namely the catalytically enhanced complex metal hydrides, is discussed. The predictions are supported by thermodynamics considerations, calculations derived from molecular orbital (MO) theory and backed up by simple chemical insights and intuition.

Thermal decomposition of the non-interstitial hydrides for the storage and production of hydrogen.

Light metal hydrides and complex hydrides for hydrogen storage.

Magnesium based materials for hydrogen based energy storage: Past, present and future

Atomic clusters, consisting of a few to a few thousand atoms, have emerged over the past 40 years as the ultimate nanoparticles, whose structure and properties can be controlled one atom at a time. One of the early motivations in studying clusters was to understand how the properties of matter evolve as a function of size, shape, and composition. Over the past few decades, more than 200 000 papers have been published in this field. These studies have not only led to a considerable understanding of this evolution from clusters to crystals, but also have revealed many unusual size-specific properties that make cluster science an interdisciplinary field on its own, bridging physics, chemistry, materials science, biology, and medicine. More importantly, the possibility of creating a new class of materials, composed of clusters instead of atoms as building blocks, has fueled the hope that one can synthesize materials from the bottom-up with unique and tailored properties. This Review focuses on the properties ...

Super Atomic Clusters: Design Rules and Potential for Building Blocks of Materials

The authors review available experimental information on the existence, thermodynamic stability and physical properties of hydrides formed by the absorption of hydrogen gas in intermetallic compounds of two transition metals. The emphasis is on stability. It is shown that empirical models for the stability of ternary hydrides can be reconciled with ideas based on the results of band structure calculations of (binary) metallic hydrides. It is concluded that metallic hydrides can be looked upon as alloys of metallic hydrogen. In addition to the thermodynamic properties of ternary metallic hydrides the authors discuss experimental information on electronic properties (magnetic, super-conductivity, band structure features) and on crystallographic and metallurgical properties (neutron scattering, nuclear and electron spin resonance, Mossbauer spectroscopy, diffusion). Applications are briefly reviewed.

https://iopscience.iop.org/article/10.1088/0034-4885/45/9/001/pdf

Hydrides formed from intermetallic compounds of two transition metals: a special class of ternary alloys

Etude par diffraction RX et de neutrons mettant en evidence une symetrie cubique et une structure type K 2 PtCl 6 . Spectres IR, Raman et Mossbauer montrant la presence d'ions [FeH 6 ] 4− octaedriques a bas spin

Dimagnesium iron(II) hydride, Mg2FeH6, containing octahedral FeH64- anions

X-ray and neutron diffraction experiments performed on Mg2Ni(H,D)x (0 ⩽ x ⩽ 3.9) confirmed the existence of a structural phase transformation at about 235 °C. The high temperature phase (a = 6.49 A, space group Fm3m) has an antifluorite-type metal structure in which the deuterium atoms surround the nickel atoms octahedrally in a disordered manner (D−Ni =1.47 A, D−Mg = 2.30 A). Refined atomic parameters of Mg2Ni as well as absorption and desorption isotherms for the deutende and hydride phases are reported.

New structure results for hydrides and deuterides of the hydrogen storage material Mg2Ni

The distribution of the deuterium atoms in the deuterated hexagonal laves-phase ZrMn2D3

The distribution of the deuterium atoms in the deuterated Laves-phase ZrV 2 D x was measured by neutron powder diffraction for deuterium concentrations x of 1.5, 2.8 and 4.9. At low deuterium concentrations only the tetrahedral interstices formed by two zirconium and two vanadium atoms are occupied whereas at medium deuterium concentrations the interstices formed by one zirconium and three vanadium atoms are also populated. At high deuterium concentrations the occupancy of the latter interstices exceeds that of the former. The interstices formed by four vanadium atoms always remain empty. The results are analysed in the light of a cellular model of hydride stability. Good agreement is found between the calculated and the observed deuterium site occupancies.

J.-J. Didisheim

Papers

Dimagnesium iron(II) hydride, Mg2FeH6, containing octahedral FeH64- anions

New structure results for hydrides and deuterides of the hydrogen storage material Mg2Ni

The distribution of the deuterium atoms in the deuterated hexagonal laves-phase ZrMn2D3

The deuterium site occupation in ZrV2Dx as a function of the deuterium concentration

The distribution of the deuterium atoms in the deuterated cubic laves-phase ZrV2D4·5