高度多孔气凝胶二氧化硅基质中FeCo合金纳米颗粒的结构表征研究
Structural characterization study of FeCo alloy nanoparticles in a highly porous aerogel silica matrix.
作者信息
Carta D, Mountjoy G, Gass M, Navarra G, Casula M F, Corrias A
机构信息
Dipartimento di Scienze Chimiche and INSTM, Università di Cagliari, S.P. Monserrato-Sestu Km 0.700, Monserrato, Cagliari, Italy.
出版信息
J Chem Phys. 2007 Nov 28;127(20):204705. doi: 10.1063/1.2799995.
A series of FeCo-SiO(2) nanocomposite aerogels having different FeCo loadings of 3, 5, and 8 wt % were prepared using a novel urea-assisted sol-gel route. The size of the nanoparticles, which was estimated using Scherrer analysis of the main peak of the x-ray diffraction pattern, varies from 3 to 8 nm. X-ray absorption fine structure (EXAFS) and x-ray absorption near edge structure (XANES) techniques at both Fe and Co K edges were used to investigate the structure of the FeCo nanoparticles. EXAFS and XANES show that FeCo nanoparticles have the typical bcc structure. Evidence of oxidation was observed in low FeCo content aerogels. Spatially resolved electron energy loss spectroscopy analysis suggests the formation of a passivation layer of predominantly iron oxide.
采用新型尿素辅助溶胶-凝胶法制备了一系列不同FeCo负载量(3 wt%、5 wt%和8 wt%)的FeCo-SiO₂纳米复合气凝胶。通过对X射线衍射图谱主峰进行谢乐分析估算出的纳米颗粒尺寸在3至8纳米之间变化。利用Fe和Co K边的X射线吸收精细结构(EXAFS)和X射线吸收近边结构(XANES)技术研究了FeCo纳米颗粒的结构。EXAFS和XANES表明FeCo纳米颗粒具有典型的体心立方结构。在低FeCo含量的气凝胶中观察到了氧化迹象。空间分辨电子能量损失谱分析表明主要形成了以氧化铁为主的钝化层。