Study On Mangetic Entropy Change Of Rare Earth Magnetic Refrigerant Materials Of GdDyFe, GdDyFeNi And GdDyFeAl

A series of magnetic refrigerant materials of GdDyFe,GdDyFeNi and GdDyFeAl were prepared with non-self consuming arc furnace. The M-T curve was measured in a field of 0.05T with a vibrating sample magnetometer to determine the Curie temperature. Choosing some temperatures near the Curie temperature, at every temperature the isothermal magnetization curve was measured in the field range of 0-1.5T. The magnetic entropy change can be calculated with the magnetization data and thermodynamical equilibrium equations. The maximum magnetic entropy change is 3.94 J/(kg ?K) for GdDyFe and 3.5J/(kg ?K) for GdDyFeNi and 3.76J/(kg ?K) for GdDyFeAl respectively. The Curie temperature of these alloys varied from 250K to 309K near room temperature. Considered the practicability, these alloys have comparatively large magnetic entropy change and low cost under a low field of 1.5T, their refrigerant temperature varied in a comparatively wide range, and we can consider using these alloys to make complex materials which are suitable for the Ericsson cycle. For the above-mentioned advantages, these alloys are suitable candidates as magnetic refrigerant materials near room temperature.We made a preliminary study on nanomaterials (Gdo.73Dyo.27)o.925Feo.o75 and (Gdo.73Dyo.27)o.925-(Feo.5Nio.5)o.o75- Compared with the respective bulk alloys, the Curie temperatures of nanomaterials reduced 16K and 14K, and the maximum magnetic entropy change reduced 1.37J/(kg ?K) and 1.19J/(kg ?K) respectively. The AS -T curves of the nanomaterials are smoother than that of the bulk materials, So nanomaterials are the magnetic refrigerant materials which are more suitable for the Ericsson cycle than the bulk materials. The nanomaterials may be good magnetic refrigerant materials in the future.