High-pressure synthesis of novel hydride in CA-TM systems

Y. Yambe, R. Kataoka, D. Kyoi, Atsunori Kamegawa, H. Takamura, M. Okada

Research output: Contribution to journalConference articlepeer-review

2 Citations (Scopus)

Abstract

Hydrogen storage materials are attracting much attention as media of storing hydrogen. High-pressure synthesis has been widely used for exploration of novel materials. We have reported that many new Mg-based hydrides or alloys have been synthesized by anvil-type apparatus under the pressure of GPa-order. In Mg - TM (TM = Nb, Ta) - H systems, it was reported that novel FCC-type hydride which is similar in crystal structure and composition to Mg 7TiH13-16 was synthesized under 8 GPa. On the other hand, there is few reports of novel Ca-based hydrides to be synthesized under high pressure. However, the compressibility of calcium is higher than that of magnesium. Thus, there is a tendency for Ca compounds to be synthesized by lower pressure than Mg ones. This study describes the synthesis of new Ca-based hydrides by this high-pressure techniques. In Ca - TM (TM = Ti, Hf, V, Nb and Ta) systems, the influence of applied pressure on present phases were investigated. For the composition of CaH2 - 14.3 mol%ZrH2 in Ca - Zr - H system, novel hydride was synthesized at 1073 K for 2 h under 5 GPa. Crystal structure of the novel hydride was found to be FCC-type with a lattice parameter of a = 0.531 nm. In addition, the thermal stability and hydrogen contents of this novel hydride were investigated. In Ca - Hf - H system, the unknown phase was observed in the sample of CaH2 - 12.5 mol%HfH2 prepared 1073 K for 2 h under 5 GPa. This unknown phase is FCC structure with lattice parameter of a = 0.528(2) nm.

Original languageEnglish
Pages (from-to)885-888
Number of pages4
JournalAdvanced Materials Research
Volume24-25
DOIs
Publication statusPublished - 2007
EventPRICM 6: The 6th Pacific Rim International Conference on Advanced Materials and Processing - Jeju Island, Korea, Republic of
Duration: 2007 Nov 52007 Nov 9

Keywords

  • High-pressure
  • Hydrides
  • Hydrogen storage alloys

ASJC Scopus subject areas

  • Engineering(all)

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