Phase transformations in some rare earth-hydrogen systems

M. H. Mintz, Z. Hadari, M. Bixon

Research output: Contribution to journalArticlepeer-review

Abstract

The ranges of stability of Pr, Nd and Sm hydrides were investigated using simultaneous TG-DTA techniques. Measurements were made over a temperature range 25-700 °C, at 700 Torr hydrogen pressure. A new, low-temperature hexagonal phase has been detected in the NdH2-NdH3 system. Its structure is similar to the hexagonal, heavier lanthanide hydride phases. However, unlike these structures the NdH3 - x hexagonal phase transforms irreversibly on heating to the f.c.c. structure, which remains metastable at room temperature. The enthalpy changes associated with the hexagonal to f.c.c. transitions in the NdH2-NdH3 and SmH2-SmH3 systems were estimated to be 1.6 ± 0.3 kcal/mole and 4 ± 0.4 kcal/mole, respectively. No phase transition has been detected in the PrH2-PrH3 system.

Original languageEnglish
Pages (from-to)331-335
Number of pages5
JournalJournal of the Less-Common Metals
Volume37
Issue number3
DOIs
StatePublished - Sep 1974

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