Nickel Ferrite Aerogels with Monodisperse Nanoscale Building Blocks—The Importance of Processing Temperature and Atmosphere

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• 作者：Katherine A. Pettigrew ; Jeffrey W. Long ; Everett E. Carpenter ; Colin C. Baker ; Justin C. Lytle ; Christopher N. Chervin ; Michael S. Logan ; Rhonda M. Stroud ; Debra R. Rolison
• 刊名：ACS Nano
• 出版年：2008
• 出版时间：April 2008
• 年：2008
• 卷：2
• 期：4
• 页码：784-790
• 全文大小：407K
• 年卷期：0
• ISSN：1936-086X

文摘

Using two-step (air/argon) thermal processing, sol−gel-derived nickel−iron oxide aerogels are transformed into monodisperse, networked nanocrystalline magnetic oxides of NiFe₂O₄ with particle diameters that can be ripened with increasing temperature under argon to 4.6, 6.4, and 8.8 nm. Processing in air alone yields poorly crystalline materials; heating in argon alone leads to single phase, but diversiform, polydisperse NiFe₂O₄, which hampers interpretation of the magnetic properties of the nanoarchitectures. The two-step method yields an improved model system to study magnetic effects as a function of size on the nanoscale while maintaining the particles within the size regime of single domain magnets, as networked building blocks, not agglomerates, and without stabilizing ligands capping the surface.