Lattice expansion for MmNi4.30 - xCoxAl0.30Mn0.40(x = 0, 0.75) studied by in situ X-ray diffraction

Daisuke Endo, Kouji Sakaki, Etsuo Akiba

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Abstract

Hydrogenation properties of MmNi4.30 - x Cox Al0.30 Mn0.40 (x = 0, 0.75) were investigated by means of in situ X-ray diffraction (XRD). The XRD profiles were analyzed by the Rietveld method to evaluate the change of lattice parameters and lattice volume. Hydrogenation-dehydrogenation of these alloys proceeded through two phases between the solid solution phase and the hydride phase. Both the phases of MmNi4.30Al0.30Mn0.40 had the hexagonal lattice with a space group of P6/mmm and those of MmNi3.55Co0.75Al0.30Mn0.40 had the orthorhombic lattice with Cmmm after initial activation. In the two-phase co-existing region, lattice volumetric ratio of both the phases showed 19% for MmNi4.30Al0.30Mn0.40, while that became 10% by partial substitution of Co for Ni with anisotropic lattice expansion. Anisotropic lattice strain related with high dislocation density was not introduced through formation of the hydride phase.

Original languageEnglish
Pages (from-to)3435-3441
Number of pages7
JournalInternational Journal of Hydrogen Energy
Volume32
Issue number15 SPEC. ISS.
DOIs
Publication statusPublished - Jan 1 2007

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All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Condensed Matter Physics
  • Energy Engineering and Power Technology

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