A detailed investigation of structure, critical behaviour and magnetocaloric properties of Ni50Mn30Sn20 (Sn20) and Ni50Mn30In20 (In20) alloys has been investigated by means of Xrays diffraction and magnetic measurements. Ni50Mn30Sn20 alloy shows a cubic austenite 2 1 structure, and undergoes a second order magnetic transition at a Curie temperature of ,1 ( 20) = 333 . However, the Ni50Mn30In20 alloy exhibits a mixture of cubic 2 1 and 2 austenite structures having Curie temperatures of ,2 ( 20) = 285 and * ( 20) = 330 , respectively. The modified Arrott plots, Kouvel-Fisher curves and critical isotherm analysis have been used to estimate the critical exponents (, , and ) around the Curie temperature. For Sn20 alloy, the reliable exponents are consistent with the mean field model, revealing long-range ferromagnetic interactions. Nevertheless, the critical exponents of In20 alloy around 330 K cannot be arranged into any of the universality classes of well-known classical standard models. The maximum entropy change under 5 T of Sn20 (∆ = 2.43 . ) is slightly higher than that of In20 (∆ = 2.05 . ). The experimental results of entropy changes are in good agreement with those calculated using Landau theory.
Structural, microstructural, and magnetic properties of Heusler Ni50Mn50−xInx (x = 5 and 10) ribbons have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS), differential scanning calorimetry (DSC), and vibrating sample magnetometry (VSM). The as quenched Ni50Mn45In5 ribbons exhibit a mixture of monoclinic 14M (a = 4.329(3) Å, b = 5.530(3) Å, and c = 28.916(3) Å), and tetragonal L10 (a = b = 3.533(3) Å, and c = 7.522(3) Å) martensite structures, while Ni50Mn40In10 ribbons display a single monoclinic 14M phase (a = 4.262(3) Å, b = 5.692(3) Å, and c = 29.276(3) Å). After three heating/cooling cycles, in the temperature range of 303–873 K, the Rietveld refinement of the XRD patterns revealed the presence of a single 14M martensite for Ni50Mn45In5 ribbons, and a mixture of cubic L21 (31%) and 14M (69%) phases for Ni50Mn40In10 ribbons. The characteristic temperatures of the martensitic transition (Astart, Afinish, Mstart, and Mfinish), the thermal hysteresis temperature width, and the equilibrium temperature decreased with increasing indium content and heating cycles. The samples show a paramagnetic like behavior in the as quenched state, and a ferromagnetic like behavior after the third heating/cooling cycle.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.