Stability of the Hydrogen Absorption and Desoption Plateaux in LaNis-H Part 3: Experimental Observations of Compositional Inhomogeneities Due to Temperature Gradients
Author(s)
KISI, EH
GRAY, EM
Griffith University Author(s)
Year published
1995
Metadata
Show full item recordAbstract
It has been predicted by Pons and Dantzer that temperature gradients due to the released enthalpy of H absorption-desorption will generate macroscopic inhomogeneities of the αβ phase proportions in metal hydrides. We used in situ X-ray diffraction and in situ neutron diffraction respectively to study the growth of β-LaNi5H at the free surface, and β-LaNi5-D in the bulk of powdered samples. It was found that a macroscopic compositional inhomogeneity does occur, and can be so severe that the free surface of the sample remains pure α phase while the bulk of the sample is rich in β phase.It has been predicted by Pons and Dantzer that temperature gradients due to the released enthalpy of H absorption-desorption will generate macroscopic inhomogeneities of the αβ phase proportions in metal hydrides. We used in situ X-ray diffraction and in situ neutron diffraction respectively to study the growth of β-LaNi5H at the free surface, and β-LaNi5-D in the bulk of powdered samples. It was found that a macroscopic compositional inhomogeneity does occur, and can be so severe that the free surface of the sample remains pure α phase while the bulk of the sample is rich in β phase.
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Journal Title
Journal of Alloys and Compounds
Volume
217
Issue
1
Subject
Physical sciences
Condensed matter physics
Materials engineering
Resources engineering and extractive metallurgy