Large magnetocaloric effect near room temperature in Mn-Fe-P-Ge nanostructured powders

Mn-Fe-P-Ge alloys are attractive candidates for affordable and high performance magnetocaloric materials (MCM). The magnetocaloric effect (MCE), crystal structure and magnetic transition of Mn-Fe-P-Ge nanostructured powders were investigated with the aim of obtaining both high relative cooling power and large entropy change. In this work, the Ge content was tuned to obtain high Delta S-M near room temperature in powder samples. With increasing Ge content, the magnetic transition temperature increases. Interestingly, large relative cooling power (RC) together with high Delta S-M were obtained near room temperature in Mn1.1Fe0.9P0.79Ge0.21 powders, the RC value is much larger than previously reported values in Mn-Fe-P-Ge alloys. To model the magnetic transition and magnetocaloric behavior, Landau theory and a modified Arrott plot were utilized, good agreement was obtained between the theoretical model and the experimental results. Our results suggest that Mn1.1Fe0.9P0.79Ge0.21 powders possess attractive magnetocaloric properties for commercial applications. (C) 2015 Elsevier B.V. All rights reserved.