Influence of Tb substitution on low-field magnetocaloric effect in Gd5Si1.72Ge2.28 alloy

The lattice parameters, magnetic phase transition, Curie temperature and magnetocaloric properties for (Gd1-xTbx)(5)Si1.72Ge2.28 alloys with x = 0, 0.15, 0.20 and 0.25 were investigated by X-ray powder diffractometry and magnetization measurements. The results show that suitable partial substitution of Tb in Gd5Si1.72Ge2.28 compound remains the first-order magnetic-crystallographic transition and enhances the magnetic entropy change, although Tb substitution decreases the Curie temperature (T-C) of the compounds. The magnetic entropy change of (Gd1-xTbx)(5)Si1.72Ge2.28 alloys retains a large value in the low magnetic field of 1.0 T. The maximum magnetic entropy change for (Gd0.80Tb0.20)(5)Si1.72Ge2.28 alloy in the magnetic field from 0 to 1.0 T reaches 8.7 J/(kg center dot K), which is nearly 4 times as large as that of (Gd0.3Dy0.7)(5)Si-4 compound (|Delta S-max| = 2.24 J/(kg center dot K), T-C=198 K).