Effect of Fe substitution on the structure and magnetocaloric effect of Mn5−xFexGeSi2 alloys

Abstract The structure and magnetocaloric effect of Mn 5− x Fe x GeSi 2 compounds were studied. Analysis of X-ray powder diffraction and energy dispersive X-Ray spectroscopy revealed that Mn 5 − x Fe x GeSi 2 alloys with x 5 Si 3 -type structure (space group P 6 3 / mcm ), maintaining the structure of Mn 5 Ge 3 ; and alloys with x =1.5 and 2 consist of the major Mn 5 Si 3 -type phase and the minor Ni 2 In-type phase (space group P 6 3 / mmc ). The results of Rietveld refinement showed that the cell parameters for the Mn 5 Si 3 -type phase decrease with increasing Fe content. The positive slopes in Arrott plots indicate that a second-order ferromagnetic to paramagnetic transition occurs. The Curie temperature increases with increasing Fe content from 182 K for x =0.6 to 224 K for x =2. The maximum magnetic entropy change of 3.7 J/(kg K) for x =0.8 was found under a magnetic field change of 0–20 kOe.