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MA: Fachverband Magnetismus
MA 16: Magnetic Particles / Clusters II
MA 16.6: Talk
Tuesday, March 27, 2012, 10:45–11:00, EB 202
Magnetic Nanorods in Ferrofluids: A Novel Template-Directed Synthesis Route — •Robert Zierold1, Soham Banerjee1, Martin Waleczek1, Josep M. Montero Moreno1, Detlef Görlitz1, Carl E. Krill III2, and Kornelius Nielsch1 — 1University of Hamburg — 2Ulm University
In this contribution a novel synthesis route for the preparation of nickel nanorod suspensions is presented, which might allow realization of new magnetic fluids displaying novel properties. Firstly, multi-segmented magnetic nanowires with a diameter of 40 nm are synthesized by electro-deposition of alternating segments of Ni and Cu into porous alumina membranes from a single electrolyte. The length of the particular phases can be tuned individually. Secondly, the release of the multi-segmented nanowires from the alumina matrix and,thirdly, the selective etching of the copper phases finally result in a novel ferrofluidic suspension in a carrier fluid. The magnetic behavior of the short nanorods (aspect ratios 2–10) is characterized in the oxide matrix as well as in liquid suspension. Furthermore, it is proven that subjecting the nanorod ferrofluid to an external magnetic field increases its (magneto)viscosity. Moreover, we find that nanorod suspensions reveal differences in shear-thinning behavior—the decrease in the magnetoviscous effect as a function of shear-frequency—compared to a ferrofluid consisting of spherical nanoparticles.
The authors gratefully acknowledge the DAAD RISE program and the State of Hamburg—throuh the Excellence Cluster "Nanotechnology in Medicine"—for financial support.