Destabilization of Mg Hydride by Self-Organized Nanoclusters in the Immiscible Mg-Ti System

Kohta Asano*, Ruud J. Westerwaal, Anca Anastasopol, Lennard P A Mooij, Christiaan Boelsma, Peter Ngene, Herman Schreuders, Stephan W H Eijt, Bernard Dam

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Mg is an attractive hydrogen storage material not only because of its high gravimetric and volumetric hydrogen capacities but also because of it low material costs. However, the hydride of MgH2 is too stable to release hydrogen under moderate conditions. We demonstrate that the formation of nanometer-sized clusters of Mg reduces the stability of MgH2 by the interface energy effect in the immiscible Mg-Ti system. Ti-rich MgxTi1-x (x <0.5) thin films deposited by magnetron sputtering have a hexagonal close packed (HCP) structure, which forms a face-centered cubic (FCC) hydride phase upon hydrogenation. Positron Doppler broadening depth profiling demonstrates that after hydrogenation, nanometer-sized MgH2 clusters are formed which are coherently embedded in an FCC TiH2 matrix. The P (pressure)-T (optical transmission) isotherms measured by hydrogenography show that these MgH2 clusters are destabilized. This indicates that the formation of nanometer-sized Mg allows for the development of a lightweight and cheap hydrogen storage material with a lower desorption temperature. (Graph Presented).

Original languageEnglish
Pages (from-to)12157-12164
Number of pages8
JournalJournal of Physical Chemistry C
Volume119
Issue number22
DOIs
Publication statusPublished - 4 Jun 2015
Externally publishedYes

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