The role of Mg2FeH6 formation on the hydrogenation properties of MgH2-FeFx composites

• Authors: Iwona Malka , Tomasz Czujko , Jerzy Bystrzycki , Leszek Jaroszewicz
• Languages of publication: EN

Abstracts

EN

The hydrogenation properties of magnesium hydride mechanically milled with iron fluorides (FeF2 and FeF3), were investigated by Temperature Programmed Desorption (TPD) and volumetric methods using a Sieverts-type apparatus, as prepared upon dehydrogenation and finally upon subsequent hydrogenation. The activation energy of hydrogen desorption (Ea), calculated from the Kissinger formula using TPD measurements obtained with different heating rates, showed significant decreases of Ea in comparison to that of milled MgH2 without any dopants. Moreover, the influence of these metal fluorides on the thermodynamics of the decomposition process was also examined. In the case of the FeF2 dopant, rehydrogenation following desorption caused the complete decomposition of the iron fluoride to BCC iron and the formation of a predominant MgH2 phase. In contrast to FeF2, the addition of FeF3 led to the formation of β-MgH2 as a major phase coexisting with Mg2FeH6 and MgF2 compounds. The presence of pure Fe in the MgH2+FeF2 composite, as opposed to MgH2+FeF3 containing Mg2FeH6 and MgF2, did not cause any significant influence on the sorption properties of MgH2. Moreover, the original material doped with FeF3 predominantly showed iron in the Mg2FeH6 compound, while the FeF2 dopant iron mostly showed the nearly pure BCC metallic phase [...]

Keywords

EN

Hydrogen storage; Magnesium hydride; Mg2FeH6 ; Iron fluorides; Activation energy

• Publisher: De Gruyter Open
• Journal: Open Chemistry
• Year: 2011
• Volume: 9
• Issue: 4
• Pages: 701-705

Dates

published

1 - 8 - 2011

online

4 - 6 - 2011

Contributors

author

Iwona Malka

• Department of Advanced Materials and Technologies, Military University of Technology, PL-00-908, Warsaw, Poland

author

Tomasz Czujko

• Department of Advanced Materials and Technologies, Military University of Technology, PL-00-908, Warsaw, Poland

author

Jerzy Bystrzycki

• Department of Advanced Materials and Technologies, Military University of Technology, PL-00-908, Warsaw, Poland

author

Leszek Jaroszewicz

• Institute of Applied Physics, Military University of Technology, PL-00-908, Warsaw, Poland

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Identifiers

DOI

10.2478/s11532-011-0051-5