Realization of Enhanced Refrigeration Capacity with Non-Hysteretic Behavior in Ni40Gd5Co5Mn37In12Si1 Alloy Near Room Temperature at 2T

Abstract

Ni–Co–Mn–In–Si-based Heusler alloys have recently attracted a lot of attention because of their superior magnetocaloric properties around the second-order magnetic transformation near room temperature. In this paper, the effects of Gd substitution (Ni45–xGdxCo5Mn37In12Si1; x = 0 and 5) and Gd addition (Ni45Co5Mn37In12Si1 + Gdx; x = 0 and 5) on thermal and magnetic hysteretic behavior of temperature- and field-dependent magnetization of Ni45Co5Mn37In12Si1 Heusler alloy were investigated. The as-prepared Ni45–xGdxCo5Mn37In12Si1 Heusler alloys crystalize into a high-temperature austenite cubic L21 crystal structure, confirmed by powder X-ray diffraction. Microstructural and elemental composition analyses from field emission scanning electron microscopy reveal that parent Ni45Co5Mn37In12Si1 alloy shows single phase with larger grains in its as-cast form, whereas the Gd-doped Ni45Co5Mn37In12Si1 sample possess some dendritic well-distinguishable Gd-rich and deficient regions. Thermomagnetic measurements show that substitution of Gd at the Ni site in Ni45Co5Mn37In12Si1 notably reduces the Curie temperature, TC, from 333 to 317 K. Thermodynamic analyses of isothermal field-dependent magnetization result in significantly large magnetic entropy change, ΔSM = −0.842 J kg–1 K–1 under an applied field change, ΔH = 2 T at 305 K across the austenite regime for Ni40Gd5Co5Mn37In12Si1. Furthermore, the maximum refrigeration capacity of ∼47 J kg–1 was achieved for the composition of Ni40Gd5Co5Mn37In12Si1 at 305 K.