Pressure-induced effects and phase relations in Mg2NiH 4

Z. Gavra, G. Kimmel, Y. Gefen, Moshe H. Mintz

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

The low-temperature (<210°C) crystallographic structure, electrical conductivity, and thermal stability of Mg2NiH4 powders compacted under isostatic pressures of up to 10 kbar were studied. A comparison is made with the corresponding properties of the noncompressed material. It has been concluded that under stress-free hydriding conditions performed below 210°C, a two-phase hydride mixture is formed. Each of the hydride particles consists of an inner core composed of an hydrogen-deficient monoclinic phase coated by a layer of a stoichiometric orthorhombic phase. The monoclinic phase has a metalliclike electrical conductivity while the orthorhombic phase is insulating. High compaction pressures cause the transformation of the orthorhombic structure into the monoclinic one, thereby resulting in a pressure-induced insulator-to-conductor transition. Reduced decomposition temperatures are obtained for the compressed hydrides. This reduction is attributed to kinetic factors rather than to a reduced thermodynamic stability.

Original languageEnglish
Pages (from-to)4548-4551
Number of pages4
JournalJournal of Applied Physics
Volume57
Issue number10
DOIs
StatePublished - 1 Jan 1985
Externally publishedYes

ASJC Scopus subject areas

  • General Physics and Astronomy

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