Theoretical and Experimental Studies of Al-Impurity Effect on the Hydrogenation Behavior of Mg

Abstract

In this paper, we study the influence of hydrogen concentration on the binding energies in magnesium hydrides. The impact of aluminum atom addition on the hydrogenation behavior of magnesium was theoretically and experimentally defined. Doping Al into the Mg lattice allows the uniform hydrogen distribution in both the fcc and bcc Mg lattice at a low hydrogen concentration (H:Mg < 0.875) to be more energetically favorable. In addition, this leads to bcc Mg lattice formation with a uniform hydrogen distribution, which is more energetically favorable than the fcc Mg lattice when the atomic ratio H:Mg is near 0.875. In addition, compared with the pure Mg, in the Al-doped Mg, the phase transition from the hcp to the fcc structure with a uniform distribution of H atoms induces less elastic strain. Thus, the uniform hydrogen distribution is more favorable, leading to faster hydrogen absorption. Pure magnesium is characterized by cluster-like hydrogen distribution, which decreases the hydrogen diffusion rate. This leads to the accumulation of a higher hydrogen concentration in magnesium with aluminum compared with pure magnesium under the same hydrogenation regimes, which is confirmed experimentally.

Improvement of the Hydrogen Storage Characteristics of MgH2 with Al Nano-Catalyst Produced by the Method of Electric Explosion of Wires

“…For this purpose, various additives were used, among which platinum group metals, such as nickel [18,19], hydride-forming Ce, New Brunswick, Ti [20], low-temperature hydrides of the LaNi 5 type [21][22][23], non-hydride-forming by the type of iron, cobalt, and chromium, positively affecting the kinetics of the sorption of magnesium-based hydrides [24,25], as well as metal oxides [8]. Three-dimensional transition metalloids and oxides could change and significantly improve the sorption kinetics [9,10,13,[26][27][28][29][30][31].…”

Microstructure Characteristics and Hydrogen Storage Kinetics of Mg77+xNi20−xLa3 (x = 0, 5, 10, 15) Alloys

“…A great deal of experimental researchers have been conducted in the last few decades to address the drawback of Mg-based alloys, such as alloying [ 19 , 20 , 21 ], nano-crystallization [ 22 , 23 , 24 ], doping catalyst [ 25 , 26 , 27 ] and exploring new treatment methods [ 28 , 29 , 30 ], etc. By alloying various transition metals (TM) with Mg, TM was found to reduce the thermal stability of MgH 2 and enhance the hydrogen reaction kinetics of MgH 2 [ 31 , 32 ].…”