Low-field magnetic entropy change in Dy(Co1−xSix)2

A series of Dy(Co1−xSix)2 (x=0, 0.01, 0.03, 0.05 and 0.07) compounds have been prepared by arc-melting method. The X-ray diffraction (XRD) analysis reveals that all samples are in the MgCu2-type structure. The magnetization were measured by a vibrating sample magnetometer (VSM). A first-order transition disappeared by partial substitution of Co by Si (x>0.05) in the Dy(Co1−xSix)2 alloys. The magnetic entropy changes (|ΔSM|) as a function of the temperature in magnetic field (1 T) for Dy(CoxSi1−x)2 have been calculated, while the maximum values of |ΔSM are 5.8, 4.1, 3.3, 3.3 and 2.6 J/kg K for x=0, 0.01, 0.03, 0.05 and 0.07, respectively. The Curie temperature (TC) can be adjusted between 142 and 168 K by partial substitution of Co for Si with some reduction of the |ΔSMax|. The origin of the large magnetocaloric effect (MCE) and the potential application of Dy(Co,Si)2 as a working material for magnetic refrigerants have also been discussed.