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A Novel Synthesis Method of La–Mg‐Ni‐based Superlattice by LaNi 5 Absorbing Gas‐state Mg
Author(s) -
Zhao Xin,
Ke Dandan,
Cai Ying,
Hu Feng,
Liu Jingjing,
Zhang Lu,
Han Shumin
Publication year - 2019
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201901191
Subject(s) - superlattice , alloy , materials science , hydrogen storage , phase (matter) , microstructure , volatilisation , crystal structure , crystal (programming language) , hydrogen , absorption (acoustics) , metal , crystallography , metallurgy , chemistry , composite material , organic chemistry , optoelectronics , computer science , programming language
La−Mg‐Ni based alloys are considered as future negative material for Ni‐MH batteries, while the volatilization of Mg hinders their application. Mg volatilization is considered irreversible in the preparation process. Herein, we provide a novel process to produce superlattice La−Mg‐Ni‐based alloy via alloying gas‐state Mg with LaNi 5 slice. The formation of superlattice structures is verified in detail by microstructure characterization and element distribution analysis. The results indicate that there exists an equilibrium state for Mg solution in the La−Mg‐Ni alloy, and the gas‐state Mg atoms are directly absorbed by the LaNi 5 alloy. With increasing the absorption time, Mg in LaNi 5 slice bends to become more homogenous. It is attributed that the integration of the gas‐state Mg atoms leads to the transformation of the crystal structure of the LaNi 5 cells on the slice surface into MgCu 4 Sn‐type phase, thus the solid LaNi 5 phase turn to liquid MgCu 4 Sn‐type phase under the high temperature. Further, the liquid phase permeates into the inside of the LaNi 5 slice along crystal boundaries which alloys with LaNi 5 lattices to form Ce 2 Ni 7 ‐type phase. This technology proves that the migration of metal atoms in gas state can induce a regroup phenomenon to form solid state crystal and provides a brand method for hydrogen storage materials preparation.