Influence of fabrication conditions on giant magnetocaloric effect of Ni–Mn–Sn ribbons

Huy Dan Nguyen, Tran Huu Do, Hai Yen Nguyen, Thi Thanh Pham, Huu Duc Nguyen, Thi Nguyet Nga Nguyen, Dang Thanh Tran, The Long Phan and Seong Cho Yu

Abstract

The magnetocaloric effect of Ni₅₀Mn_50−xSn_x ribbons (x = 11–15) prepared by using melt-spinning and subsequent annealing has been investigated. The x-ray diffraction data of specimens show that all the samples are partially crystallized with Ni₂MnSn phase. The magnetic transitions of these ribbons strongly depend on Sn-concentration and annealing process. Particularly, the antiferromagnetic–ferromagnetic transition is just observed at a narrow range of the Sn-concentration (x = 12–14). The positive magnetic entropy changes occurring at the transition temperature of the antiferromagnetic phase are quite large, |ΔS_m|_max = 5.7 J kg⁻¹ K⁻¹ (for x = 13) with external magnetic field change ΔH = 12 kOe. Besides that, the negative magnetic entropy changes take place near Curie temperature and their magnitude is also large, |ΔS_m|_max = 1.9 J kg⁻¹ K⁻¹ (for x = 13). The obtained results indicate that Ni₅₀Mn_50−xSn_x ribbons are good candidates for magnetic refrigeration application at room temperature