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
Volume509
Pages3746-3750
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)
Abstract

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.

URL<Go to ISI>://000287968000009
DOI10.1016/j.jallcom.2010.12.194
Alternate JournalJ. Alloy. Compd.