顆粒間交互作用對奈米鎳粉末巨觀磁行為的影響

• Main Authors: Shih-Heng Huang, 黃是衡
• Other Authors: Wen-Hsien Li
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/11706014232202723277

碩士 === 國立中央大學 === 物理研究所 === 99 === The Ni nanoparticles were fabricated by the thermal evaporation method. The chemical composition of the samples are pure Ni and NiO by X-ray diffraction and General Structure Analysis System. The mean particle diameter of Ni nanoparticles are 9 nm determined using X-ray diffraction patterns. We controled the distance among particles by means of pressing the very loosely packed nanoparticle powder samples, characterized by the compacting density (CD) of the samples that ranging from 1 % to 70 % of the density of bulk Ni. By experimental data of nickel nanoparticles, we observed, first, the saturation magnetization Ms increase and then slightly decrease when the packing fraction increase, and this phenomenon is due to the interaction between magnetic moments. Second, the saturation magnetization Ms will decrease when temperature rise, we study this phenomenon by the spin-wave model under the assumption that only the Heisenberg interaction between the magnetic moment. In the study of coercivity magnetic phenomena, We observed that with the packing fraction and temperature increases, both will make a downward trend in magnetic coercivity. When use the simulation result of reference to explain the phenomenon, lead to that the surface and inside surface magnetic moment of nickel nanoparticle will arrange in the more consistent, when the packing fraction increase.