Magnetic entropy change in bulk nanocrystalline Gd metals

The magnetocaloric properties of the as-consolidated nanocrystalline and coarse-grained gadolinium metals were studied in the present work. With the decrease of Gd grains from micrometer to nanometer range, magnetic entropy change drops surprising from 10.07 to 4.47 J kg(-1) K-1 at a magnetic-field change of 5 T, and their resultant magnetic entropy change uniformly peaks at 294, 290, and 288 K, respectively, corresponding to the magnetic transition temperature of the three samples. The Curie temperature T-C of the nanocrystalline Gd shifts by more than 6 K below that of coarse-grained Gd sample. However, the values of magnetic entropy change of the nanocrystalline metals exhibit a more constant tendency compared with the coarse-grained sample. The Arrott plots indicate the second-order character of magnetic phase transition still in the nanocrystalline Gd metals. The refrigerant capacity calculated is also used to evaluate material refrigeration capacity.