Investigation On Rare Earth Gd-Based Magnetic Refrigerants

In this paper the lattice parameters, magnetic phase transition, Curie temperature and magnetocaloric effect in the samples R(Co_1-xSn_x)₂ with x = 0, 0.025, 0.050, 0.075, 0.100 and the GdTbSiGe system alloys have been investigated by X-ray powder diffraction, metallographic analysis and magnetization measurement.1. The cubic MgCu₂-type structure for the samples of RCo₂ was confirmed by X-ray powder diffraction and the rest samples consist of the RCo₂ phase mainly, together with some RCo₃ and R₅Sn₃ impurity phases. The Curie temperatures and magnetic phase transition of the samples are confirmed by M-T curves and Arrott plots. The magnetic phase transition in the samples DyCo₂ and Dy(Co_0.975Sn_0.025)₂ is the first-order transition, all the rest samples remain the second-order transition. The Curie temperatures of the samples increase with increasing Sn contents. The maximum magnetic entropy change in the samples Tb(Co_1-xSn_x)₂ (x=0, 0.025) are 3.44, 2.29 J.kg^-1.K^-1 and in the Dy(Co_1-xSn_x)₂ ( x =0, 0.025, 0.050, 0.075) samples are 5.78, 5.43, 3.88, 2.98 J.kg^-1.K^-1 respectively in the applied field change of 0-2.0 T.2. A small amount of the Tb substitution in Gd₅Si_1.72Ge_2.28 compound can...