Effect of Si substitution on the Structural, Magnetic and Magnetocaloric Properties of Ni–Mn–In Heusler alloys

Abstract

The effect of partial substitution of manganese by silicon in Ni47Mn40−xSixIn13 (x = 1, 2, 3) on the structural (martensitic), magnetic transitions and associated magnetocaloric properties around the martensitic transition of these alloys, was investigated. The alloys exhibited the single austenite structure at the room temperature. The lattice contraction was observed with an increase in Si content, thereby inducing the FM and AFM interactions between manganese atoms, which further influence the magnetic and martensitic transitions. The increase in Si concentration was observed with the decrease in valence electron to atom ratio (e/a ratio) and thus influencing the martensitic transitions. The transition temperatures such as martensitic transition (TM) and the Curie transition (TC) of the austenite phase decrease with increasing Si-content. With the increase in Si content from x = 1 to 3, the TM was found to decrease from 259 to 169 K. A high magnetic entropy change (∆S)M of 12.3, 3.1 and 30.6 J kg−1 K−1 was observed for the x = 1, 2, and 3 alloys at their respective martensitic transitions for a magnetic field of 2 T.