Structural studies of hydrogen storage alloys using x-ray/neutron diffraction and total scattering

Yumiko Nakamura, Hyunjeong Kim, Saishun Yamazaki, Kouji Sakaki, Thomas Proffen, Etsuo Akiba

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

Crystal and local structures and hydrogen occupation of Mg containing materials, (Mg,Ca)Ni x(x = 2, 3) intermetallic compounds and a MgCo metastable alloy, have been investigated using in-situ and ex-situ X-ray/neutron diffraction and total scattering. A C15 Laves phase (Mg 0.67Ca 0.33)Ni 2 showed isotropic lattice expansion upon hydrogenation. Mg and Ca occupied the same site randomly. It has two hydrogen sites, Mg(Ca) 2Ni 2 site and M(Ca)Ni 3 site. Mg 2CaNi 9, MgCa 2Ni 9, and CaNi 3 compounds consisted of MgZn 2-type (Mg,Ca) 2Ni 4 cell and CaCu 5-type CaNi 5 cell stacking along the c-axis. The MgZn 2-type cell was occupied by only Mg in Mg 2CaNi 9, and randomly occupied by both Mg and Ca in MgCa 2Ni 9. Expansion of this cell strongly depended on the composition: larger expansion was observed in a Ca-rich composition. Local structure of a Mg-Co alloy synthesized by mechanical alloying has been studied using the PDF (Pair Distribution Function) method. The analysis suggested that material contained two 1-2 nm domains with different compositions and local structures, i.e. Mg-rich and Co-rich domains, and hydrogen was located only in the Mg-rich domain.

Original languageEnglish
Title of host publicationRecent Developments in Materials for Hydrogen Storage and Carbon-Capture Technologies
Pages13-17
Number of pages5
DOIs
Publication statusPublished - Dec 1 2011
Event2011 MRS Spring Meeting - San Francisco, CA, United States
Duration: Apr 25 2011Apr 29 2011

Publication series

NameMaterials Research Society Symposium Proceedings
Volume1334
ISSN (Print)0272-9172

Other

Other2011 MRS Spring Meeting
CountryUnited States
CitySan Francisco, CA
Period4/25/114/29/11

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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