The effect of Pd on hydride formation in Zr(PdxM1−x)2 intermetallics where M is a 3d element

D. Babai, M. Bereznitsky, R. Z. Shneck, I. Jacob

Research output: Contribution to journalArticlepeer-review

Abstract

We report how the substitution of 3d metal atoms M by Pd in Zr(PdxM1−x)2 pseudobinary compounds affects the stability of the corresponding hydrides. For the lighter elements in the M=3d metal row, V and Cr, the Pd substitution creates less stable hydrides while it yields almost no change in the stability of the hydrides for Mn, of the middle of the 3d row. We further demonstrate that the two factors determining the stability of the hydrides of these compounds are the heat of formation of the compound, ΔHalloy, and its crystal volume, V. Using a combination of these two parameters we predict that the substitution of the heavier 3d metals Fe and Co by Pd stabilizes the Zr(PdxM1−x)2 hydrides, i.e. they would require lower hydrogenation pressures than those necessary for ZrFe2 and ZrCo2 hydride formations. These findings support other authors’ theoretical prediction for ZrPdFe hydride formation. The empirically fitted constants that link ΔHalloy and V are related to the energies needed to expand or compress the crystal lattice and thus have basic physical meaning. We further evaluate the critical temperatures, Tc, for Zr(PdxMn1−x)2-H2 systems from the experimental pressure hysteresis in the absorption-desorption loops. This enables us to show that the electronic contribution to the H-H interaction in the ZrM2 hydride is unexpectedly neutral for M=Mn, it is positive, i.e. repulsive, for the lighter 3d element M=Cr, and surprisingly negative, i.e. attractive, for the binary PdH0.6 hydride.

Original languageEnglish
Article number161503
JournalJournal of Alloys and Compounds
Volume889
DOIs
StatePublished - 5 Jan 2022

Keywords

  • Hydrogen absorbing materials
  • Hydrogen-hydrogen electronic interaction
  • Metal to hydride phase transition: hydrogen-hydrogen elastic interaction
  • Thermodynamic properties
  • Zr(PdM), M-3d metal, pseudobinary intermetallics

ASJC Scopus subject areas

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

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