Shape Evolution of Single-Crystalline Iron Oxide Nanocrystals

• Published in: Journal of the American Chemical Society 2004-02, Vol.126 (7), p.1950-1951
• Main Authors: Cheon, Jinwoo, Kang, Nam-Jung, Lee, Sang-Min, Lee, Jae-Hyun, Yoon, Ji-Hyun, Oh, Sang Jun
• Format: Article
• Language: English
• Subjects: Clusters, nanoparticles, and nanocrystalline materials; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Physics; Structure of solids and liquids; crystallography
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja038722o

Shape- and size-controlled synthesis of single-crystalline maghemite (γ-Fe2O3) nanocrystals are performed by utilizing a solution-based one-step thermolysis method. Modulating the growth parameters, such as the type and amount of capping ligands as well as the growth time, is shown to have a significant effect on the overall shape and size of the obtained nanocrystals and on the ripening process itself. The resulting shapes of the novel structures are diverse, including slightly faceted spheres, diamonds, prisms, and hexagons, all of which are in fact truncated dodecahedron structures with different degrees of truncation along the {111}, {110}, or {100} faces. Spherical nanocrystals are easily assembled into the three-dimensional superlattices, demonstrating the uniformity of these nanocrystals. The size-dependent magnetic properties are examined, and large hexagon-shaped γ-Fe2O3 nanocrystals are shown to be ferrimagnetic at room temperature.