Solid-State Hydriding Mechanism in the LiBH4 + MgH2 System

The LiBH4 + MgH2 system has great potential in reversible hydrogen storage for fuel cell vehicles. However, it has always been dehydrogenated and rehydrogenated in the liquid state until recently. The solid-state hydriding and dehydriding are necessary in order to achieve hydrogen uptake and release near ambient temperature. In this study, the solid-state hydriding mechanism of 2LiH + MgB2 mixtures has been investigated. It is found that the solid-state hydriding proceeds in two elementary steps. The first step is the ion exchange between the Mg2+ and Li+ ions in the MgB2 crystal to form an intermediate compound (Mg1-xLi2x)B-2. The second step is the continuous ion exchange and simultaneous hydrogenation of (Mg1-xLi2x)B-2 to form LiBH4 and MgH2. This finding is consistent with the observed diffusion-controlled hydriding kinetics.close3

Nitrides of Non‐Main Group Elements

Abstract In the last two decades, there has been a renewed interest in the chemistry of nitrides and nitridometalates. Both binary and higher nitrides MxNy have already featured prominently as refractory materials, corrosion‐ and mechanical wear‐resistant coatings, hard materials, and hard magnets; thin films are used as diffusion barriers in integrated circuits. Whereas research on binary transition metal nitrides is mostly driven by technical and economic interests, the investigation on nitridometalates primarily focuses on exploration with respect to the development of new synthetic strategies and the design of new materials. Within this field of interest, especially the nitride chemistry of rare earth metals is still comparably undeveloped. Chemical bonding in binary nitrides varies from primarily salt‐like via covalent to metallic, whereas nitridometalates are best described as containing covalent complex anions [MxNy]z− with alkali, alkaline earth, or rare earth metal cations providing electroneutrality