Magnetocaloric effect over a wide temperature range due to multiple magnetic transitions in GdNi0.8Al1.2 alloy

摘要

The magnetic properties, magnetocaloric effect (MCE) and refrigerant capacity (RC) of the novel polycrystalline GdNi0.8Al1.2 alloy are investigated. The temperature dependence of magnetization exhibits multiple magnetic transitions at T-1 = 17.7 K, T-2 = 46.7 K and T-3 = 256 K thereby displaying a complex magnetic behaviour. The magnetocaloric effect is calculated in terms of the magnetic entropy change (-Delta S-M), from isothermal magnetization data using Maxwell relations. The maximum magnetic entropy change at major transitions T-2 is 9.15 J kg(-1) K-1 (for a field change of 0-9 T) and 4.20 J kg(-1) K-1 (0-5 T) and at T-3 is 1.10 J kg(-1) K-1 (0-9 T) and 0.67 J kg(-1) K-1 (0-5 T). The overlap of the two -Delta S-M peaks expeditiously expand the working temperature range of this material with substantial MCE which in turn yields moderate RC value of 120 J/kg for a field change of 0-5 T. These results suggest that the GdNi0.8Al1.2 alloy may be a meaningful candidate for magnetic refrigeration working in a wide temperature range.