The magnetic phase transition and magneto- caloric effect of Gd5Si1.85Ge2.15 alloy are studied. The alloy was prepared from distilled commercial gadolinium. The major impurities (in wt.%) in the distilled commercial Gd are 0.016 O, 0.0054 C, and 0.0016 N. The impurities are higher than those in the high pure Gd but lower than those in commercial Gd. The results of X-ray diffraction and magnetic susceptibility show that there exists the first-order magnetic phase transition in the Gd5Si1.85Ge2.15 alloy at 253 K. The maximum of magnetic entropy change Smax is 12.5 J/kg·K near the temperature of magnetic phase transition in the alloy.
