Phase Structure of (La_,Mg_,Nd)₅Ni₁₉ Hydrogen Storage Alloy

Abstract:

The crystal structure of (La,Mg,Nd)₅Ni₁₉ alloy has been investigated using powder x-ray diffraction. A Rietveld refinement is used to determine the phase structures for tying to find out the correlations of lattices among the phases in this hydrogen storage alloy. The results show that the alloy consists of three phases, which correspond to (La,Mg)₃Nd₂Ni₁₉ with a Pr₅Co₁₉-type structure, La (Mg,Nd)Ni₇ phase with a Ce₂Ni₇-type structure and (La,Mg)₃Nd₂Ni₁₉ with a Ce₅Co₁₉-type structure. Mg and Nd substitute for La atom at the 4f position for Pr₅Co₁₉-type and Ce₂Ni₇-type structures and the 6c position for Ce₅Co₁₉-type structure, respectively. It induces a good lattice match along the a-axisand b-axis among the three phases. The three kinds of structures might form a rod-like shape structural unit by stacking along the c-axis. This phase constitution seems to be beneficial for the cyclic stability of the hydrogen storage alloys.

• Periodical: Applied Mechanics and Materials (Volume 455)
• Pages: 66-70
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.455.66
• Online since: November 2013
• Authors: Qiang He, Yong Quan Guo, Zhen Zhen Zheng
• Keywords: (La,Mg,Nd)₅Ni₁₉ Hydrogen Storage Alloy, Phase Structure, Rietveld Analysis

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