Alloys*

Magnetocaloric materials exhibiting a second-order phase transition (SOPT) near room temperature have attracted much attention because these materials are free from magnetic and thermal hysteresis, and may show large cooling efficiency and moderate magnetic entropy change. We have investigated (Nd_1-xCe_x)YFe₁₅ (x = 0 - 1) alloys prepared by arc melting and vacuum annealing. The x-ray diffraction patterns analyzed using the Rietveld method shows that the samples crystallized in the rhombohedral Th₂Zn₁₇-type structure with space group R-3m. The thermomagnetic curves M(T) measured at μ₀H = 1T show smooth SOPT with Curie temperatures near 300 K. The values of peak magnetic entropy change (ΔS_M,max) and relative cooling power (RCP) measured at 3 T increase with increasing Nd concentration reaching 4.20 Jkg^-1K^-1 and 285 Jkg^-1 for (Nd_0.7Ce_0.3)YFe₁₅. The measured ΔS_M and RCP values are relatively high as compared to those of other Gd-free compounds showing magnetocaloric effect due to SOFT near room temperature. This suggests that the (Nd_1-xCe_x)YFe₁₅ alloys have potential for room temperature magnetic refrigeration.