Structural, magnetic and magnetocaloric properties of Heusler alloys Ni50Mn38Sb12 with boron addition

We report on the structural, magnetic and magnetocaloric properties of the Ni50Mn38Sb12Bx alloys in term of boron addition with x = 1, 3 and 5. We have found that both the paramagnetic–ferromagnetic austenitic transition (TC) and the ferromagnetic–antiferromagnetic martensitic transition (TM) are sensitively influenced by the boron addition: TC tends to increase, while TM decreases with increasing boron concentration. Temperature dependent X-ray diffraction in the range of 200–500 K clearly shows an evolution of the structural transformation from orthorhombic to cubic structure phase transition on heating for the x = 1 and 3 samples. Strikingly, the addition of boron atoms into the lattice favours the ferromagnetic ordering relatively to the antiferromagnetic arrangement below TM. This consequently affects on the magneto-structural transition as well as on the size of magnetocaloric effect.

► We investigate the influence of the additional boron atoms on the structural, magnetic and magnetocaloric properties of Heusler alloys Ni50Mn38Sb12Bx with x = 1, 3, and 5.
► We found that both the paramagnetic–ferromagnetic austenitic transition (TC) and the ferromagnetic–antiferromagnetic martensitic transition (TM) are tunable by varying the boron concentration.
► Temperature dependent X-ray diffraction clearly shows a martensitic–austenitic magneto-structural transformation on heating.
► Interestingly, the addition of boron atoms into the lattice favours the ferromagnetic ordering relatively to the antiferromagnetic arrangement below TM. This consequently affects on the magneto-structural transition as well as the size of magnetocaloric effect at TM.