Magnetic properties of Mn3-xFexSn compounds with tuneable Curie temperature by Fe content for thermomagnetic motors

Abstract

Mn3-xFexSn system (0.00 <= x <= 3.00 with Delta x = 0.25) alloys present the Curie temperature (T-C) or transition temperature (T-T) tuneable by the Fe content. A piece-wise linear profile for T-C,T-T as a function of x is observed in a two wide temperature ranges, between 155 K up to 759 K and 259 K up to 155 K. Their equations are T-C,T-T = (59 +/- 15) + (240 +/- 7) . x and T-C,T-T = (257 +/- 1) - (206 +/- 4) . x, respectively. The alloys are low cost and easy manufacturing, rare earth free, with second order magnetic transition (SOMT), and have good magnetic properties. These features suggest an immediate application of the material in cascade thermomagnetic motors that operate with a large temperature range between hot and cold sources. Furthermore, SOMT Mn-Fe-Sn system materials are also reported with advantages that could make alloys of the Mn3-xFexSn system, (0.88 < x < 1.20), promising candidate for magnetic refrigeration. The typical ferromagnetic behaviour is achieved only by samples with x >= 1. The samples with x between 0.00 and 0.75 do not show the saturation magnetization even using fields up to 13 T. (C) 2017 Elsevier B.V. All rights reserved.