Dy(Co_0.5Ni_0.5)₂合金磁熵变的研究

Magnetic Entropy Change of Dy(Co_0.5Ni_0.5)₂

我们采用电弧熔炼和真空热处理的方法制备了Dy(Co0.5Ni0.5)2合金,通过该合金的等温磁化曲线,对其相变类型和磁卡效应展开研究。根据Arrott曲线和Inoue-Shimizu模型确定Dy(Co0.5Ni0.5)2合金的相变属于二级相变。根据等温磁化曲线的数据计算了Dy(Co0.5Ni0.5)2合金的熵变,计算结果表明随着磁场的增加熵变值不断增加,且在外加磁场相同时,熵变值在居里温度附近达到最大值。在30 kOe的磁场中,Dy(Co0.5Ni0.5)2磁熵变和制冷系数分别为6.86 J/kg∙K和235.78 J/kg。通过与其它文献所报道的Laves相合金相对比,可以知道Dy(Co0.5Ni0.5)2的制冷系数要优于大多数Laves相合金。

Dy(Co0.5Ni0.5)2 alloy was synthesized by arc melting and subsequent annealing. We have studied magnetocaloric effect (MCE) and transition order by isothermal magnetization curves. According to Arrott curve and Inoue-Shimizu model, the phase transition of Dy(Co0.5Ni0.5)2 alloy belongs to the second-order phase transition. The entropy change of Dy(Co0.5Ni0.5)2 alloy is calculated based on the data of isothermal magnetization curves. The results show that the entropy change increases with the increase of magnetic field. In the case of the same external magnetic field, the entropy change of Dy(Co0.5Ni0.5)2 reaches the maximum near Curie temperature. The maximum magnetic entropy change and the refrigerant capacity of Dy(Co0.5Ni0.5)2 alloy are 6.86 J/kg∙K and 235.78 J/kg in a magnetic field of 30 kOe. By comparing with Laves compounds reported in other literatures, it can be seen that the refrigerant capacity of Dy(Co0.5Ni0.5)2 is better than that of other compounds.