A core-shell phenomenon maintain the magnetocaloric properties of the ternary silicide Gd6Co1.67Si3 during water flux ageing

JOURNAL OF ALLOYS AND COMPOUNDS

卷:584

Article

Chennabasappa, Madhu¹  Chevalier, Bernard¹  Lahaye, Michel²  Labrugere, Christine^1,2  Toulemonde, Olivier¹ 

[1] Univ Bordeaux, CNRS, ICMCB, UPR 9048, F-33608 Pessac, France

[2] Univ Bordeaux, ICMCB, CeCaMA, F-33600 Pessac, France

关键词: Ageing;    Gadolinium based intermetallics;    Magnetocaloric effect;    XPS;    AES;    EPMA;   

DOI  :  10.1016/j.jallcom.2013.08.211

来源: Elsevier

【 摘 要 】

Ageing effect phenomenon is artificially stimulated on room temperature magnetocaloric material Gd6Co1.67Si3 by using constant flux of water up to time interval of 3 months. A core-shell model of oxide layer formation (SiOx-Gd2O3) on surface of Gd6Co1.67Si3 due to corrosion is justified using spontaneous single metal electrochemical reactions. The model is first proposed by a detailed microstructure study using Electron Probe Micro-Analysis, X-ray diffraction experiments on the aged slab revealing Gd2O3 phase and elemental depth profile analysis against time by Auger spectroscopy. It is further supported by surface chemical bonding study using X-ray Photoelectron Spectroscopy (XPS) concentrated on Si2p and O1s spectra. It is finally demonstrated that the room temperature bulk magnetocaloric performances of the material are not affected even under formation of corroded layer at the micron level scale. The Gd2O3 shell certainly acts as a passivation layer. (C) 2013 Elsevier B. V. All rights reserved.

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