Magnetostructural transition and magnetocaloric effect in highly textured Ni-Mn-Sn alloy Available to Purchase

Ni_49.4Mn_38.5Sn_12.1 near single crystal was obtained by the Bridgman method. At room temperature, it consisted of a mixture of the parent austenite phase with the cubic L2₁ Heusler structure (a_c = 5.984 Å) and modulated, tetragonal martensite phase 4M (a_t = 4.337 Å, c_t = 5.655 Å). Under the application of a magnetic field, the specimen undergoes field induced reverse martensitic transformation, which combined with the Curie transition in austenite leads to the coexistence of direct and inverse magnetocaloric effects. The maximum entropy change at 280 K and under 5 T amounts to 3.4 J·kg⁻¹·K⁻¹ for the structural transition and at 316 K reaches −2.7 J·kg⁻¹·K⁻¹ for the magnetic transformation. The magnetic entropy change occurs over a wide temperature span leading to improved refrigerant capacity of 101 J·kg⁻¹ (5 T). Hysteretic losses are considerably reduced, which is promising with respect to improved cyclic stability of such a material.