XPS研究Fe_2O_3纳米粒子表面包覆无机膜

Surface Properties of Inorganic Coated Fe_2O_3 Nanoparticles Characterized by XPS

针形铁黄纳米粒子表面包覆无机物如Si、Co等氧化物形成复合纳米粒子,是改善金属磁性记录粉性能的重要方式.采用ICP,TEM,XPS方法研究复合纳米粒子的表面性质,结果表明包硅复合粒子的表面形成均匀、致密的SiO2薄膜,表面层与基体表面间的界面结构类似异质结,导致粒子的XPS谱图中 Fe 2p谱峰发生2.7eV的化学位移;而包钴复合粒子由于钴在铁黄表面的吸附发生在部分晶面上而无法形成均匀、致密的薄膜,XPS谱图主要发生因表面荷电而导致的物理位移.

Coating the surface of goethite nanoparticles by Si, Co oxides layer is one of the most important methods to improve the magnetic properties of metal magnetic recording particles. The surface electronic properties of the coated nanoparticles were studied by using XPS. Results show that there is a close, uniform, firm and ultra thin SiO(2) layer formed on the surface of hematite nanoparticles. Silica coating treatment changes the properties of the hematite cores significantly since the binding energy of Fe 2p electrons shows significant shift related to the spectrum of the untreated hematite particles. The chemical shift of the binding energy is more than 2.7eV. A possible interpretation for the shift of such spectral features is that the contact interface surface of silica layer and the hematite particle surface is similar to P-N heterojunction. The cobalt oxides are adsorbed on part of the crystal face of Fe(2)O(3) particles, and the binding energy of whole XPS spectrum mainly shows physical shift about 4.4eV due to the surface charge.