中文摘要：

GdNi5 nanoparticles and GdNi5/Gd2O3nanocapsules（with GdNi5 core and Gd2O3 shell） were prepared by arcdischarge technique under different hydrogen partial pressure.The GdNi5 nanoparticles show irregular spherical shape and have a size distribution of 10—50 nm with an average diameter of 15 nm.In comparison,the GdNi5/Gd2O3 nanocapsules present spherical morphology and show a size distribution of 10—100 nm with an average diameter of 60 nm.Under a magnetic field change of 50 kOe,the maximum magnetic entropy change of GdNi5 nanoparticles is 13.5 J/（kg K） at 5 K,while the corresponding value of the GdNi5/Gd2O3nanocapsuels is only 5.7 J/（kg K） at 31 K.The origin of the large magnetic entropy change of GdNi5nanoparticles is ascribed to its high atomic moments and small anisotropy energy barrier induced by its small particle size.

英文摘要：

GdNi5 nanoparticles and GdNis/Gd2O3 nanocapsules （with GdNi5 core and Gd2O3 shell） were prepared by arcdischarge technique under different hydrogen partial pressure. The GdNi5 nanoparticles show irregular spherical shape and have a size distribution of 10-50 nm with an average diameter of 15 nm. In comparison, the GdNi5/Gd2O3 nanocapsules present spherical morphology and show a size distribution of 10-100 nm with an average diameter of 60 nm. Under a magnetic field change of 50 kOe, the maximum magnetic entropy change of GdNi5 nanoparticles is 13.5 J/（kg K） at 5 K, while the corresponding value of the GdNis/Gd2O3 nanocapsuels is only 5.7 J/（kg K） at 31 K. The origin of the large magnetic entropy change of GdNi5 nanoparticles is ascribed to its high atomic moments and small anisotropy energy barrier induced by its small particle size.