Magnetocaloric effect in Nd(Co_(0.8)Fe_(0.2))_2 Laves compound with wide operating temperature

摘要

The magnetocaloric effect (MCE) and transition order inNd(Co0.8Fe0.2)2Laves phase compound were studied by dc magnetization measurement. In order to make the inexpensive NdCo2Laves phase compound for room-temperature magnetic refrigeration possible, the Curie temperature of the NdCo2(∼100 K) was tuned to 263 K with 20 at.% of Fe substituting for Co. An entropy change of 1.66 J/kg K was obtained inNd(Co0.8Fe0.2)2at 265 K under an external magnetic field change of 30 kOe. Meanwhile, a wide operating temperature range of 102 K for MCE and a large refrigerant capacity of 121.6 J/kg at an external field change of 30 kOe were observed. Specially, at an external field change of 20 kOe, the operating temperature ofNd(Co0.8Fe0.2)2(81 K) is even twice wider than that of Gd (39 K). To confirm the transition order of the compound, Banerjee criterion as well as the universal scaling of the magnetocaloric effects were employed. These two criteria agree well with each other, indicating a second-order transition inNd(Co0.8Fe0.2)2.