可控粒径及一维链状纳米Fe_3O_4的制备

Preparation of Sized-controlled and One-dimensional Chain Nano-Fe_3O_4 Particles

采用氧化共沉淀相转化法,控制适当的pH(9～11.5)和反应温度(20～100℃),制备了不同粒径(20.6～45.0 nm)的纳米Fe3O4,同时对纳米Fe3O4一维成链的影响因素进行了分析.研究发现:磁场强度和溶液的pH值对纳米Fe3O4一维成链有影响,磁场强度在低于75 mT,pH值在9～11.5时,Fe3O4呈现一维链状排列,且成链趋势随pH值的减小而增强.纳米Fe3O4粒子的链状结构是由外部磁场和其表面电荷的协同效应影响的.纳米Fe3O4均呈现出铁磁性行为,一维链状纳米Fe3O4具有相对较大的矫顽力和剩磁.

The preparation of variable-sized（20.6～45.0 nm） Fe3O4 nanocrystals using oxidation-coprecipitation phase transformation,changing the pH values（9～11.5） and temperature（20～100 ℃） of the system was described.The effects of magnetic intensity and pH on the formation of the one-demensional（1D） Fe3O4 nano-particles were studied.The results showed that the magnetic fields and pH values can affect the assembly of the 1D Fe3O4 nano-particles.When the pH values were in the range of 9～11.5 under the external magnetic fields（75 mT）,the Fe3O4 nano-particles showed the 1D chain structure.The tendency of the Fe3O4 1D chain increased with the decreasing of pH.The formation of the 1D chain structure was at-tributed to the synergy of the exterior magnetic fields and the surface charge of the Fe3O4 nano-particles.The Fe3O4 nanocrystals displayed ferromagnetic behavior.Fe3O4 particles with 1D chain structure have the higher coercivity and remanence.