Effect of Fe-substitution on microstructure, hysteresis behaviour and magnetocaloric effect in Gd5Si2Ge2 Alloys

Effect of Fe-substitution on the phase formation, partitioning behaviour of Fe in the co-existing phases, magneto-structural transition, magnetic entropy change and associated hysteresis losses has been investigated in Gd₅Si₂Ge₂ alloy. The virgin alloy crystallizes in monoclinic Gd₅Si₂Ge₂-type phase, while Fe-substituted alloys form mixed monoclinic Gd₅Si₂Ge₂-type and orthorhombic Gd₅Si₄-type phases. Electron probe microanalysis reveals that Fe does not dissolve in the matrix, but influences the magneto-structural transitions. Magneto-structural characterization of the Fe-containing alloys reveals that the Fe-substitution suppresses the structural transition observed at 273 K in virgin alloy. A maximum magnetic entropy change, ΔS_M of 6.5 J/kg-K at 273 K was observed for a field change of 2 T in Gd₅Si₂Ge₂ alloy. The Fe-substituted alloys exhibit lower value of ΔS_M but with reduced hysteresis losses.