Regensburg 2007 – scientific programme
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DF: Fachverband Dielektrische Festkörper
DF 12: Electric, Electromechanical and Optical Properties II
DF 12.3: Talk
Friday, March 30, 2007, 11:30–11:50, H11
The influence of particle agglomeration on the dielectric and magnetic properties of a nanocomposite — •Béatrice Hallouet1, Bernd Wetzel2, and Rolf Pelster1 — 1Fachrichtung 7.2, Experimentalphysik, Universität des Saarlandes Postfach 151150, 66 041 Saarbrücken, Germany — 2Institut für Verbundwerkstoffe (IVW GmbH), University of Kaiserslautern D-67663 Kaiserslautern, Erwin-Schrödinger Str. Geb. 58, Germany
We have investigated a composite consisting of magnetic nanoparticles (magnetite) in a polymer matrix. We study permittivity and permeability for different particle concentrations using dielectric measurements in the frequency range from 5 Hz to 1 GHz as well as magnetic measurements from 10 MHz to 6 GHz. The measured permittivity shows already a relaxation of the pure matrix which is enhanced by the addition of particles. We use the spectral representation of Bergman in order to show that this effect is partly due to a polarization of the conducting particles, and partly due to a change of molecular polarisability at the interfaces between particles and matrix. The high frequency permittivity reflects the existence of the agglomerates. Combining this structural information and the measured permeability, the spectral representation allows us to evaluate the intrinsic permeability of the nanoparticles. In addition the ferromagnetic resonance is analyzed and it is shown that the resonance frequency doesn't depend on the filling factor.