Effects of manganese doping on magnetocaloric effect in Ge-rich Gd5Ge2.05Si1.95 alloy

The structure, magnetic and magnetocaloric properties of the Ge-rich Gd5Ge2.05–xSi1.95–xMn2x (x=0.01 and 0.03) alloys were investigated by scanning electron microscopy, X-ray powder diffraction, differential scanning calorimeter (DSC) and magnetization measurements. The results of energy dispersive X-ray analysis (EDX) and X-ray diffraction analyses showed that the composition and crystal structure of the alloys were desired. DSC measurements were performed to determine the transformation temperatures for each alloy. Both alloys exhibited the first order phase transition around room temperature. The alloys showed an anti-ferromagnetic transition around 60 K. The isothermal magnetic entropy changes of the alloys were determined from the isothermal magnetization measurements by using the Maxwell relation. The maximum values of isothermal magnetic entropy change of the Gd5Ge2.05–xSi1.95–xMn2x alloy with x=0.01 was found to be −12.1 and −19.8 J/(kg·K) using Maxwell equation around 268 K in applied fields of 2 and 5 T, respectively.