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

The magnetocaloric effect of Ni50Mn50?xSnx 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, |?Sm|max?=?5.7?J?kg?1?K?1 (for x?=?13) with external magnetic field change ?H?=?12?kOe. Besides that, the negative magnetic entropy changes take place near Curie temperature and their magnitude is also large, |?Sm|max?=?1.9?J?kg?1?K?1 (for x?=?13). The obtained results indicate that Ni50Mn50?xSnx ribbons are good candidates for magnetic refrigeration application at room temperature.