| Autor: |
Shumin Han, Yuan Li, Lu Zhang, Linda Che, Junling Zhang, Jinding Wang, Jingjing Liu |
| Rok vydání: |
2014 |
| Předmět: |
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| Zdroj: |
Journal of Alloys and Compounds. 582:552-557 |
| ISSN: |
0925-8388 |
| DOI: |
10.1016/j.jallcom.2013.08.099 |
| Popis: |
An investigation of the phase formation mechanism and electrochemical properties of the La 0.75− x Nd x Mg 0.25 Ni 3.3 ( x = 0, 0.15) alloys has been conducted in this paper. As explored by Rietveld analysis of the XRD data, the La 0.75 Mg 0.25 Ni 3.3 alloy is composed of Ce 2 Ni 7 -type and Gd 2 Co 7 -type phases accompanied by minor CaCu 5 -type phase. The partial substitution Nd for La benefits the formation of Gd 2 Co 7 -type phase, indicating that the atoms with smaller radius favor the formation of the Gd 2 Co 7 -type phase. However, CaCu 5 -type phase disappears with Nd substitution. Because part of the replaced La atoms transform into [A 2 B 4 ] subunits with the Ni atoms, and the formed [A 2 B 4 ] subunits crystallize with [AB 5 ] subunits to produce A 2 B 7 -type phase, resulting in the depletion of the minor CaCu 5 -type phase. The electrochemical P–C isotherms present that the La 0.60 Nd 0.15 Mg 0.25 Ni 3.3 alloy only containing A 2 B 7 -type phase has one single plateau while the La 0.75 Mg 0.25 Ni 3.3 alloy which contains minor LaNi 5 phase has two plateaus. It is beneficial for the elevation of equilibrium plateau pressure ascribing to the contraction in cell volumes by Nd substitution. Electrochemical measurements show that the substitution of La by Nd improves the discharge capacity and the high rate dischargeability owing to the increase of A 2 B 7 -type phase abundance. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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