Hydrogen absorption and desorption by Mg67-xCa xNi33 powders prepared by mechanical alloying

Akito Takasaki, Kazuya Sasao

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Mg67-xCaxNi33 elemental powder (0≤x≤20) mixtures were mechanically alloyed by a planetary ball mill, and phase variations after mechanical alloying (MA) and subsequent hydrogenation by gas phase loading at temperatures of 373 and 503 K, and their hydrogen desorption were investigated. The MA leaded to the formation of the Mg 2Ni-type phase for all powders. All powders containing Ca were induced to form an amorphous-like phase after hydrogenation at 373 K for 168 h, although the binary Mg67Ni33 powder was the α-phase (Mg2NiH0.3 hydride). After hydrogenation at 503 K, on the other hand, the low temperature (LT)-phase (Mg2NiH4 hydride) formed for all powders. The ternary powders also formed the CaH 2 hydrides. The temperature for the maximum hydrogen desorption rate increased with increasing Ca concentration in the powders after hydrogenation at both temperatures. The activation energies for hydrogen desorption for the binary powder after hydrogenation at 373 and 503 K were the same, about 92 J mol-1, and those for Mg47Ni33Ca20 powder at 373 and 503 K were about 168 and 244 J mol-1, respectively, indicating that substitution of Ca for Mg stabilized the hydrides.

Original languageEnglish
Pages (from-to)431-434
Number of pages4
JournalJournal of Alloys and Compounds
Volume404-406
Issue numberSPEC. ISS.
DOIs
Publication statusPublished - 2005 Dec 8

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Mechanical alloying
Powders
Hydrogen
Desorption
Hydrogenation
Hydrides
Temperature
Ball mills
Substitution reactions
Activation energy
Gases

Keywords

  • Calcium
  • Hydrogen storage
  • Magnesium-nickel alloy
  • Mechanical alloying

ASJC Scopus subject areas

  • Metals and Alloys

Cite this

Hydrogen absorption and desorption by Mg67-xCa xNi33 powders prepared by mechanical alloying. / Takasaki, Akito; Sasao, Kazuya.

In: Journal of Alloys and Compounds, Vol. 404-406, No. SPEC. ISS., 08.12.2005, p. 431-434.

Research output: Contribution to journalArticle

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AB - Mg67-xCaxNi33 elemental powder (0≤x≤20) mixtures were mechanically alloyed by a planetary ball mill, and phase variations after mechanical alloying (MA) and subsequent hydrogenation by gas phase loading at temperatures of 373 and 503 K, and their hydrogen desorption were investigated. The MA leaded to the formation of the Mg 2Ni-type phase for all powders. All powders containing Ca were induced to form an amorphous-like phase after hydrogenation at 373 K for 168 h, although the binary Mg67Ni33 powder was the α-phase (Mg2NiH0.3 hydride). After hydrogenation at 503 K, on the other hand, the low temperature (LT)-phase (Mg2NiH4 hydride) formed for all powders. The ternary powders also formed the CaH 2 hydrides. The temperature for the maximum hydrogen desorption rate increased with increasing Ca concentration in the powders after hydrogenation at both temperatures. The activation energies for hydrogen desorption for the binary powder after hydrogenation at 373 and 503 K were the same, about 92 J mol-1, and those for Mg47Ni33Ca20 powder at 373 and 503 K were about 168 and 244 J mol-1, respectively, indicating that substitution of Ca for Mg stabilized the hydrides.

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