Magnetocaloric properties of Mnx(Fe, Ni)5-xSi3 for room-temperature magnetic refrigeration

Abstract

A series of Mnx(Fe0.5Ni0.5)5-xSi3 compounds (with x = 2, 2.1, 2.3, 2.5, and 2.7), which undergo a second-order magnetic transition, are prepared to evaluate their potential for room-temperature magnetic refrigeration. The peak magnetic entropy change values for Mnx(Fe0.5Ni0.5)5-xSi3 are −2.73 J kg−1 K−1 (x = 2), −3.09 J kg−1 K−1 (x = 2.1), −3.20 J kg−1 K−1 (x = 2.3), −3.73 J kg−1 K−1 (x = 2.5), and −3.15 J kg−1 K−1 (x = 2.7) at µ0∆H = 3 T. In addition, a detailed analysis of the magnetic phase transition is conducted by calculating the critical exponents, which form the basis for estimating magnetocaloric properties. Furthermore, a custom-built testbed for magnetic refrigeration is used to compare the cooling capability of Mnx(Fe0.5Ni0.5)5-xSi3 against Gd. Although the peak entropy changes for Mnx(Fe0.5Ni0.5)5-xSi3 is limited ∼ 50 % of Gd, Mnx(Fe0.5Ni0.5)5-xSi3 achieves 68 % of the temperature span produced by Gd. Considering the material cost advantage and the possibility of a composite refrigerant by compositionally tuning the Curie temperature, Mnx(Fe0.5Ni0.5)5-xSi3 without thermal hysteresis can be an economical alternative for practical magnetic refrigeration at room temperature.