The influence of Ge substitution on the magnetostucture transition and magnetocaloric effect of Mn-Ni-Sn-Ge alloys

This paper investigates the effects of Ge addition on the martensitic transition (MT) and magnetic properties in the Mn-rich ferromagnetic shape memory alloys of Mn2Ni1.6Sn0.4−xGex. The increase of Ge content leads to a rapid increase of the MT temperature but a gradual decrease of the Curie temperature of austenitic phase. Field-induced metamagnetic phase transition was confirmed and the MT temperatures decreased by about 7 K under the magnetic field of 30 kOe for x = 0.02. Large magnetic entropy changes were observed around MT temperatures, which would be ascribed to the temperature- and field-induced MT in Mn2Ni1.6Sn0.4−xGex alloys. The hysteresis losses and effective refrigerant capacities for these alloys were discussed in this paper.