The structure and magnetocaloric effect of rapidly quenched Gd5Si2Ge2 alloy with low-purity gadolinium

A magnetic refrigerating material Gd5Si2Ge2 was prepared by arc-melting method under argon atmosphere with low-purity commercial gadolinium. The structure and magnetocaloric effect (MCE) of the as-cast and rapidly quenched Gd5Si2Ge2 alloys were investigated by means of X-ray diffraction and magnetic measurements. The as-cast Gd5Si2Ge2 consists of Gd5Si2Ge2-type, Gd5Si4-type, Gd5(Si,Ge)3 and Gd(Si,Ge) phases from powder XRD results. The alloys quenched at a velocity of 25 m/s or 40 m/s both adopt in a single phase with orthorhombic Gd5Si4-type structure. The lattice parameters under different quenched velocities calculated by least-squares method have no significant difference. After being rapidly quenched at 40 m/s, the Curie temperature of Gd5Si2Ge2 is about 303 K and its maximum magnetic entropy change is 7.25 J/kg K (0–5 T).