The effect of Cr doping on the magnetic and magnetocaloric properties of Ni45Co5Mn36.5In13.5 Heusler alloys

Abstract

Herein, Ni_45−xCr_xCo₅Mn_36.5In_13.5 (x = 0, 0.2, 0.4, and 0.6 at%) and Ni₄₅Co₅Mn_36.5−yCr_yIn_13.5 (y = 0.2, 0.4, and 0.6 at%) polycrystalline Heusler alloys are prepared by arc melting and then characterized using X-ray diffraction and a vibrating sample magnetometer. A single L2₁ austenitic phase is confirmed at room temperature. Meanwhile, we studied the effect of Cr doping on the magnetic properties of Ni₄₅Co₅Mn_36.5In_13.5 alloys. It is observed that, with the incorporation of Cr atoms, both the lattice constant and valence electron concentration of the alloys have changed, resulting in the phase transition temperature, saturation magnetization and magnetic entropy changing significantly. In addition, when Cr is replaced by Mn, the change of phase transition temperature (ΔT) induced by the magnetic field decreases; therefore, in the Ni₄₅Co₅Mn_36.1Cr_0.4In_13.5 samples, the magnetic entropy change reaches a maximum value of up to 37.1 J kg⁻¹ K⁻¹ under an external magnetic field of 3T, which is more than 50% higher than that of other Ni–Mn based Heusler alloys reported in the literature.