Tunable Magnetocaloric Properties of Gd-Based Alloys by Adding Tb and Doping Fe Elements.

In this paper, the magnetocaloric properties of GdTb alloys were studied and the optimum composition was determined to be GdTb. On the basis of GdTb, the influence of different Fe-doping content was discussed and the effect of heat treatment was also investigated. The adiabatic temperature change (ΔT) obtained by the direct measurement method (under a low magnetic field of 1.2 T) and specific heat capacity calculation method (indirect measurement) was used to characterize the magnetocaloric properties of GdTb ( = 00.4) and (GdTb)Fe ( = 00.15), and the isothermal magnetic entropy (ΔS) was also used as a reference parameter for evaluating the magnetocaloric properties of samples together with ΔT. In GdTb alloys, the Curie temperature (T) decreased from 293 K ( = 0) to 257 K ( = 0.4) with increasing Tb content, and the GdTb alloy obtained the best adiabatic temperature change, which was 3.5 K in a magnetic field up to 1.2 T (T = 276 K). When the doping content of Fe increased from = 0 to = 0.15, the T of (GdTb)Fe ( = 00.15) alloys increased significantly from 276 K ( = 0) to 281 K ( = 0.15), and a good magnetocaloric effect was maintained. The annealing of alloys (GdTb)Fe ( = 0~0.15) at 1073 K for 10 h resulted in an average increase of 0.3 K in the maximum adiabatic temperature change and a slight increase in T. This study is of great significance for the study of magnetic refrigeration materials with adjustable Curie temperature in a low magnetic field.