Novel hydrides in Mg-TM systems synthesized by high pressure (TM = Zr, Nb, Hf and Ta)

Masuo Okada, Yasuyuki Goto, Riki Kataoka, Yuichi Yambe, Atsunori Kamegawa, Hitoshi Takamura

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

High-pressure synthesis has been widely used for exploration of novel materials. In this study, new Mg-based ternary hydrides in Mg-TM-H systems (TM = Zr, Nb, Hf and Ta) have been prepared under a pressure of 5 GPa by using a cubic-anvil-type apparatus. In TM = Zr, Nb and Hf, MgTM2Hy with a monoclinic-type structure were synthesized at 923 K under 5 GPa. Lattice parameters of MgTM2Hy were a = 5.816 Å, b = 3.3569 Å, c = 8.519 Å, β = 103.06° (for TM = Zr); a = 5.70 Å, b = 3.2888 Å, c = 7.927 Å, β = 103.06° (for TM = Nb); a = 5.782 Å, b = 3.317 Å, c = 8.507 Å, β = 103.06° (for TM = Hf). Results from fusion extraction analysis for MgTM2Hy (TM = Zr, Nb and Hf) showed their hydrogen contents, giving chemical formula of MgTM2H5.9. In TM = Nb and Ta, ternary hydrides with an FCC-type structure were synthesized under 5 GPa. These FCC hydrides had lattice parameters of a = 9.5526 Å (TM = Nb) and 9.5376 Å (TM = Ta). For TM = Nb, hydrogen content was determined from the fusion extraction analysis to be 5.8 mass%, corresponding to Mg6.2NbH14. Among the newly found hydrides, Mg6.2NbH14 showed the lowest dehydrogenation temperature of 595 K with endothermic reaction. Crystal structures and thermal stabilities of these hydrides were also investigated.

Original languageEnglish
Pages (from-to)6-10
Number of pages5
JournalJournal of Alloys and Compounds
Volume446-447
DOIs
Publication statusPublished - 2007 Oct 31

Keywords

  • High-pressure synthesis
  • Magnesium
  • Mg-Hf-H
  • Mg-Nb-H
  • Mg-Ta-H
  • Mg-Zr-H
  • New hydride
  • X-ray diffraction

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry

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