Effect of Ca on the microstructure and magnetocaloric effects in the La1-xCaxFe11.5Si1.5 compounds

TitleEffect of Ca on the microstructure and magnetocaloric effects in the La1-xCaxFe11.5Si1.5 compounds
Publication TypeJournal Article
Year of Publication2011
AuthorsZhang H, Long Y, Cao Q, Zou M, Gschneidner KA, Pecharsky VK
Journal TitleJournal of Alloys and Compounds
Date Published03
Type of ArticleArticle
ISBN Number0925-8388
Accession NumberISI:000287968000009
Keywordselectron, ex, lafe13-xsix intermetallic compounds, Lanthanum iron silicide, magnetic entropy change, magnetic hysteresis, magnetocaloric effect, metamagnetic transition, partial substitution, REDUCTION, room-temperature, Scanning electron microscopy (SEM)

The effect of Ca on the microstructure and magnetocaloric effects has been investigated in the La1-xCaxFe11.5Si1.5 (x = 0, 0.1, 0.2 and 0.3) compounds. The introduction of Ca leads to the appearance of minor alpha-Fe and Ca-rich phases, which affects the actual compositions of the main phases for the Ca containing samples. With increasing the Ca concentration, the Curie temperature T-C increases from 183 to 208 K, and the maximum magnetic entropy changes vertical bar Delta S vertical bar at the respective T-C with a magnetic field change from 0 to 5 T are 21.3, 19.5, 16.9, and 11.2 J/kgK for x = 0, 0.1, 0.2, and 0.3, respectively. The nature of the magnetic transition changes from first-order to second-order with an increase in Ca concentration, which leads to a reduction of the hysteresis and a decrease of the magnetic entropy change. However, the relative cooling power for La1-xCaxFe11.5Si1.5 compounds remains comparable with or even larger than that of other magnetocaloric materials over a wide temperature range. The higher T-C and the smaller hysteresis in comparison with those of the parent compound suggest that the La1-xCaxFe11.5Si1.5 compounds could be suitable candidates for magnetic refrigerants in the corresponding temperature range. (C) 2011 Elsevier B.V. All rights reserved.

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Alternate JournalJ. Alloy. Compd.