Nanocrystalline Iron Oxide Aerogels as Mesoporous Magnetic Architectures
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- 作者：Jeffrey W. Long ; Michael S. Logan ; Christopher P. Rhodes ; Everett E. Carpenter ; Rhonda M. Stroud ; and Debra R. Rolison
- 刊名：Journal of the American Chemical Society
- 出版年：2004
- 出版时间：December 29, 2004
- 年：2004
- 卷：126
- 期：51
- 页码：16879 - 16889
- 全文大小：682K
- 年卷期：v.126,no.51(December 29, 2004)
- ISSN：1520-5126
文摘
We have developed crystalline nanoarchitectures of iron oxide that exhibit superparamagneticbehavior while still retaining the desirable bicontinuous pore-solid networks and monolithic nature of anaerogel. Iron oxide aerogels are initially produced in an X-ray-amorphous, high-surface-area form, byadapting recently established sol-gel methods using Fe(III) salts and epoxide-based proton scavengers.Controlled temperature/atmosphere treatments convert the as-prepared iron oxide aerogels into nanocrystalline forms with the inverse spinel structure. As a function of the bathing gas, treatment temperature,and treatment history, these nanocrystalline forms can be reversibly tuned to predominantly exhibit eitherFe3O4 (magnetite) or 
-Fe2O3 (maghemite) phases, as verified by electron microscopy, X-ray and electrondiffraction, microprobe Raman spectroscopy, and magnetic analysis. Peak deconvolution of the Raman-active Fe-O bands yields valuable information on the local structure and vacancy content of the variousaerogel forms, and facilitates the differentiation of Fe3O4 and -Fe2O3 components, which are difficult toassign using only diffraction methods. These nanocrystalline, magnetic forms retain the inherentcharacteristics of aerogels, including high surface area (>140 m2 g-1), through-connected porosityconcentrated in the mesopore size range (2-50 nm), and nanoscale particle sizes (7-18 nm). On thebasis of this synthetic and processing protocol, we produce multifunctional nanostructured materials witheffective control of the pore-solid architecture, the nanocrystalline phase, and subsequent magneticproperties.
-Fe2O3 (maghemite) phases, as verified by electron microscopy, X-ray and electrondiffraction, microprobe Raman spectroscopy, and magnetic analysis. Peak deconvolution of the Raman-active Fe-O bands yields valuable information on the local structure and vacancy content of the variousaerogel forms, and facilitates the differentiation of Fe3O4 and -Fe2O3 components, which are difficult toassign using only diffraction methods. These nanocrystalline, magnetic forms retain the inherentcharacteristics of aerogels, including high surface area (>140 m2 g-1), through-connected porosityconcentrated in the mesopore size range (2-50 nm), and nanoscale particle sizes (7-18 nm). On thebasis of this synthetic and processing protocol, we produce multifunctional nanostructured materials witheffective control of the pore-solid architecture, the nanocrystalline phase, and subsequent magneticproperties.