Phase evolution and magnetocaloric effect of melt-spun Mn3Sn2-xMx (M = B, C; x = 0-0.5) ribbons

The effects of B and C substitution for Sn on phase components, Curie temperature TC, and magnetocaloric effect of melt-spun Mn3Sn2-xMx (M B, C; x = 0-0.5) ribbons have been investigated. X-ray diffraction (XRD) results show that the main phase in the as-spun Mn3Sn2-xMx (M = B, C; x 0-0.5) ribbons is Mn3Sn2 of Ni3Sn2-type (Pnma). Minor Mn2B (when x ≥ 0.1) or Mn5C2 (when x > 0.1) secondary phase is formed, and their amounts increase with increasing B and C concentration, respectively. The Curie temperature TC of these ribbons varies in the temperature range of 240-250 K. The peak values of the maximal magnetic entropy change, -ΔSMmax, are about 13.6-18.3 mJ/cm3 K for B-substituted ribbons and 13.6-17.5 mJ/cm3 K for C-substituted ribbons, respectively, at a maximum applied field of 50 kOe. These values are about one fifth that of Gd (81.4 mJ/cm3 K). However, the relatively broader temperature range of the half maximum of ΔSM peak (∼100 K), low-cost and nontoxic elements still make Mn3Sn2-based ribbons the promising candidates for magnetic refrigeration applications close to room temperature.