Influence of the nature of the magnetic phase transition on the associated magnetocaloric effect in the Ni–Mn–Ga system
Influence of the nature of the magnetic phase transition on the associated magnetocaloric effect in the Ni–Mn–Ga system
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DOI：
10.1016/j.jmmm.2004.12.004
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发表时间：
2005-06
影响因子：
2.7
通讯作者：
Xuezhi Zhou;Wei Li;H. Kunkel;Gwyn P. Williams
中科院分区：
文献类型：
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作者：
Xuezhi Zhou;Wei Li;H. Kunkel;Gwyn P. Williams
广泛的测量磁化等温线和磁场和温度依赖的交流磁化率Ni-Mn-Ga合金的总结。这些数据的详细分析提供了一个定量评估的磁相变在这个系统中，通过建立一阶磁/马氏体结构转变和交叉线在连续的磁转变的变磁边界。在Ni55.2Mn18.6Ga26.2的“调谐”成分下，获得了ΔSm=−20.4× 104 ergsg − 1 K −1（−20.4Jkg− 1 K −1）的巨磁热效应（在317 K，50 kOe（5 T）磁场下），这是由于同时表现出一阶和二阶特性的两个跃迁的本质重合。
A summary of extensive measurements of magnetisation isotherms and of the field- and temperature-dependent AC susceptibility for Ni–Mn–Ga alloys is presented. Detailed analysis of these data provide a quantitative appraisal of the magnetic phase transitions in this system through the establishment of metamagnetic boundaries at first-order magnetic/martensitic structural transitions and crossover lines at continuous magnetic transitions. At the “tuned” composition Ni55.2Mn18.6Ga26.2a giant magnetocaloric effect with ΔSm=−20.4×104ergsg−1K−1(−20.4Jkg−1K−1) (at 317K in a 50kOe (5T) field) is achieved, and this is shown to result from the essential coincidence of two transitions exhibiting both first- and second-order characteristics simultaneously.