Structural properties of (Ti, Zr)(Mn, Cr)2M0.1(M = none, Fe, Co, Ni, and Cu) hydrogen storage alloys: Composition distribution and occupied site of doped element

Tessui Nakagawa, Daichi Heshiki, Hiroki Higa, Junko Kawakami, Riki Kobayashi, Nobuko Hanada, Kazutaka Ikeda, Toshiya Otomo, Hironori Ofuchi, Masayoshi Ishida

Research output: Contribution to journalArticlepeer-review

Abstract

CO2 tolerance of hydrogen storage alloys of AB2-type (C14 Laves phase) Ti0.515Zr0.485Mn1.2Cr0.8M0.1 (AB2-M, M = none, Fe, Co, Ni, and Cu) depends on dopant M. Since our goal is to clarify this mechanism, we determined the elemental analysis using X-ray absorption spectroscopy (XAS), scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), and neutron powder diffraction (NPD) with Rietveld refinement in this study. As a result of XAS analysis, a strong evidence of all doped elements occupying B site in AB2 was obtained. SEM-EDX showed inhomogeneous composition with vacancy in B site and linear correlation of Ti/Zr and Mn/Cr ratio. The peak width in XRD patterns of AB2-M depends on the magnitude of homogeneity, therefore the Rietveld analysis using NPD patterns could not be well refined. Thus, homogeneity is not important but element of B site would be important for CO2 tolerance as well as AB5 type alloys.

Original languageEnglish
Pages (from-to)899-904
Number of pages6
JournalMaterials Transactions
Volume62
Issue number6
DOIs
Publication statusPublished - 2021

Keywords

  • Energy dispersive X-ray spectroscopy
  • Hydrogen storage alloys
  • Neutron diffraction
  • X-ray absorption spectroscopy
  • X-ray diffraction

ASJC Scopus subject areas

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

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