This review deals with the destabilization methods for improvement of storage properties of metal hydrides. Both theoretical and experimental approaches were used to point out the influence of various types of defects on structure and stability of hydrides. As a case study, Mg, and Ni based hydrides has been investigated. Theoretical studies, mainly carried out within various implementations of DFT, are a powerful tool to study mostly MgH₂based materials. By providing an insight on metal‐hydrogen bonding that governs both thermodynamics and hydrogen kinetics, they allow us to describe phenomena to which experimental methods have a limited access or do not have it at all: to follow the hydrogen sorption reaction on a specific metal surface and hydrogen induced phase transformations, to describe structure of phase boundaries or to explain the impact of defects or various additives on MgH₂stability and hydrogen sorption kinetics. In several cases theoretical calculations reveal themselves as being able to predict new properties of materials, including the ways to modify Mg or MgH₂that would lead to better characteristics in terms of hydrogen storage. The influence of ion irradiation and mechanical milling with and without additives has been discussed. Ion irradiation is the way to introduce a well‐defined concentration of defects (Frankel pairs) at the surface and sub‐surface layers of a material. Defects at the surface play the main role in sorption reaction since they enhance the dissociation of hydrogen. On the other hand, ball‐milling introduce defects through the entire sample volume, refine the structure and thus decrease the path for hydrogen diffusion. Two Severe Plastic Deformation techniques were used to better understand the hydrogenation/dehydrogenation kinetics of Mg‐ and Mg₂Ni‐based alloys: Equal‐Angular‐Channel‐Pressing and Fast‐Forging. Successive ECAP passes leads to refinement of the microstructure of AZ31 ingots and to instalment therein of high densities of defects. Depending on mode, number and temperature of ECAP passes, the H‐sorption kinetics have been improved satisfactorily without any additive for mass H‐storage applications considering the relative speed of the shaping procedure. A qualitative understanding of the kinetic advanced principles has been built. Fast‐Forging was used for a “quasi‐instantaneous” synthesis of Mg/Mg₂Ni‐based composites. Hydrogenation of the as‐received almost bi‐phased materials remains rather slow as generally observed elsewhere, whatever are multiple and different techniques used to deliver the composite alloys. However, our preliminary results suggest that a synergic hydrogenation / dehydrogenation process should assist hydrogen transfers from Mg/Mg₂Ni on one side to MgH₂/Mg₂NiH₄on the other side via the rather stable a‐Mg₂NiH_0.3, acting as in‐situ catalyser.

The effect of mechanical milling on the thermal behavior of pyrophyllite ore from a deposit in Parsovici, Bosnia and Herzegovina, was characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and Particle size distribution. The thermal behavior of the material was followed by thermogravimetric and differential thermal analysis and correlated to its microstructural properties. The Williamson-Hall model was used to calculate the crystallite size and microstrain. Mechanochemical treatment of pyrophyllite ore produced a substantial structural modification, mainly along the c axis, resulting in disorder and partial degradation of the crystal structure of the ore. The particle size diminution, induced defects, and microstrain in the crystal lattice cause decrease in the peak intensity until the final disappearance. As confirmed by scanning electron microscopy and particle-size-distribution analysis, the surface area and the agglomeration is more pronounced as grinding time increases. Dehydroxylation of the minerals in the unmilled ore was realized at 716oC confirm by FTIR analysis. The endothermic peak that corresponds to dehydroxylation is shifted toward lower temperatures and becomes broad giving rise to the formation of amorphous SiO2 as milling time increases.