Magnetic entropy change and magnetocaloric effect of DyNiSi <inf>3</inf> , Dy <inf>2</inf> Ni <inf>3</inf> Si <inf>5</inf> , DyNiSi <inf>2</inf> and HoNiSi <inf>0.33</inf> Ga <inf>67</inf> antiferromagnets

Magnetic properties, magnetic entropy change and magnetocaloric effect of the polycrystalline SmNiGe 3 -type DyNiSi 3 , U 2 Co 3 Si 5 -type Dy 2 Ni 3 Si 5 , CeNiSi 2 -type DyNiSi 2 and CeCu 2 -type HoNiSi 0.33 Ga 0.67 antiferromagnets have been studied by bulk magnetization measurements. In field of 100 Oe DyNiSi 3 , Dy 2 Ni 3 Si 5 , DyNiSi 2 and HoNiSi 0.33 Ga 0.67 show Néel temperature (T N ) of 21 K, 19 K, 9 K and 4 K, respectively. At 2 K, above critical field (H crit ) of 28 kOe for DyNiSi 3 , 10 kOe for Dy 2 Ni 3 Si 5 , 25 kOe for DyNiSi 2 and ∼1 kOe for HoNiSi 0.33 Ga 0.67 they are soft ferromagnets and HoNiSi 0.33 Ga 0.67 shows ferromagnetic ordering below T C = 5 K in a field of 5 kOe. Magnetic entropy changes (ΔS m ) of DyNiSi 3 , Dy 2 Ni 3 Si 5 , DyNiSi 2 and HoNiSi 0.33 Ga 0.67 exhibit high-temperature negative and low temperature positive components around Néel temperature up to critical field with decreasing and disappearance of positive component of ΔS m above critical field, which indicates the transformation from antiferromagnetic to ferromagnetic states. From these compounds, HoNiSi 0.33 Ga 0.67 shows largest magnetic entropy change of −15.4 J/kg⋅K at 8 K for a field change of 0–50 kOe.