Magnetocaloric properties of NdxGd5-xSi4Mn0.5Cr0.5 (x = 0.5, 1, 1.5)

In this work, the magnetocaloric effect (MCE) of NdxGd5-xSi4M1 (x = 0.5, 1, 1.5, M: Cr and Mn) compounds were evaluated. The compounds consisted of multiple phases: (Nd, Gd)5Si4, (Nd, Gd)5Si3, GdMnSi and Cr with (Nd, Gd)5Si4 as the main phase. The addition of Mn produced the ferromagnetic GdMnSi impurity phase while suppressing nucleation of the antiferromagnetic GdSi phase, which improves MCE properties. All the compounds underwent a second-order transition whose transition temperature decreased with increasing Nd fraction, allowing TC to be tailored as required. The ΔSM|pk values for NdxGd5-xSi4M1 are 4.2 J kg−1 K−1 (at 310 K) for x = 0.5, 3.5 J kg−1 K−1 (at 294 K) for x = 1.0, and 3.28 J kg−1 K−1 (at 273 K) for x = 1.5 with a field change of 0–3 T. The maximum values of ΔTad were 0.73 K (at 273 K) for x = 0.5, 1 K (at 292 K) for x = 1.0, and 1.35 K (at 315 K) for x = 1.5 with a field change of 0–0.8 T, respectively. Thus, although the MCE properties of these compounds were inferior compared with those of Gd, these compounds exhibit a wider operating window and have potential application in a composite refrigerant for the active magnetic refrigeration cycle.