Effect of Ca on the microstructure and magnetocaloric effects in the La1−xCaxFe11.5Si1.5 compounds
Effect of Ca on the microstructure and magnetocaloric effects in the La1−xCaxFe11.5Si1.5 compounds
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DOI：
10.1016/j.jallcom.2010.12.194
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发表时间：
2011-03
影响因子：
6.2
通讯作者：
Haiming Zhang;Y. Long;Q. Cao;M. Zou;K. Gschneidner;V. Pecharsky
中科院分区：
文献类型：
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作者：
Haiming Zhang;Y. Long;Q. Cao;M. Zou;K. Gschneidner;V. Pecharsky
研究了Ca对La 1 −xCaxFe11.5Si1.5（x=0，0.1，0.2和0.3）化合物的微观结构和磁热效应的影响。Ca的引入导致少量α-Fe相和富Ca相的出现，这影响了含Ca样品的主相的实际组成。随着Ca含量的增加，居里温度TC从183 K增加到208 K，最大磁熵发生变化|ΔS|当x=0、0.1、0.2和0.3时，在磁场从0变化到5 T的相应TC下，分别为21.3、19.5、16.9和11.2J/kgK。随着Ca浓度的增加，磁转变的性质由一阶转变为二阶，从而导致磁滞回线的减小和磁熵变的减小。然而，La 1-xCaxFe11.5Si1.5化合物的相对冷却能力在很宽的温度范围内与其他磁热材料相当，甚至更大。与母体化合物相比，较高的TC和较小的滞后表明La 1-xCaxFe11.5Si1.5化合物可以成为相应温度范围内磁制冷剂的合适候选者。
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 α-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 TCincreases from 183 to 208K, and the maximum magnetic entropy changes |ΔS| at the respective TCwith a magnetic field change from 0 to 5T are 21.3, 19.5, 16.9, and 11.2J/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−xCaxFe11.5Si1.5compounds remains comparable with or even larger than that of other magnetocaloric materials over a wide temperature range. The higher TCand the smaller hysteresis in comparison with those of the parent compound suggest that the La1−xCaxFe11.5Si1.5compounds could be suitable candidates for magnetic refrigerants in the corresponding temperature range.