Magnetocaloric Effect in Ga-Free Ni50Mn34×16 (X = In, Sn, and Sb) Heusler Alloys

ABSTRACT The structural and magnetic transitions of Ni50Mn34×16 (X = Sn, Sb, and In) Heusler alloys have been investigated by thermomagnetic M(T) measurements through heating/cooling cycles. These alloys undergo structural transition from an austenite phase to a martensite phase in the temperature regime around 200 K. The martensitic transformation spans a wide temperature range (78–180 K), with thermal hysteresis characteristics of a first-order nature. In the structural transition regime, Ni50Mn34In16 shows a signature of field-induced transition from a martensite to austenite phase. At room temperature all of the alloys show a ferromagnetic austenite phase. Direct and inverse magnetocaloric properties and refrigeration capacity (RC) in these alloys were evaluated for a maximum field change of 15 kOe. In substitution reveals the largest ΔSm value of 3.0 J kg−1 K−1 at the martensitic (132 K) transition and −2.5 J kg−1 K−1 at the magnetic (316 K) transition. The magnitudes of the conventional magnetocalor...