Hydrogen induced amorphization of LaMgNi4 phase in metal hydride alloys. (3rd August 2015)

• Record Type: Journal Article
• Authors: Young, K.; Ouchi, T.; Shen, H.; Bendersky, L.A.
• Is Part Of: International journal of hydrogen energy. Volume 40:Number 29(2015)
• Page Start: 8941
• Page End: 8947
• Publication Date: 2015-08-03
• Subjects: Hydrogen absorbing alloys -- Hydrogen induced amorphization -- Metal hydride electrode -- Transmission electron microscope -- Re-crystallization; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2015.05.017
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Hydrogen induced amorphization (HIA) of the LaMgNi4 phase at 30 °C was found in three LaMgNi4 /LaNi5 two-phase metal hydride (MH)-forming alloys. The amorphization happened at the first dehydrogenation cycle from a fully hydrided alloy, and the process is reversible after annealing at 250 °C for 1 h. The hydrogen storage capacity of the LaMgNi4 phase in an amorphous state is higher than in its crystalline form. A scanning electron microscope study did not observe any significant changes in the shape of grains as a consequence of HIA and re-crystallization. A transmission electron microscope study confirmed the amorphous structure of the LaMgNi4 phase after HIA. These findings suggest a new way to improve the performance of MH alloys when used in electrochemical applications. Highlights: Hydrogen intruded amorphization in LaMgNi4 phase is found at room temperature. The amorphized LaMgNi4 phase returns to micro-crystalline after annealing. The amorphized LaMgNi4 phase has a higher hydrogen storage capacity. TEM confirms an amorphous structure with nano-crystallites.