Nuclear magnetic resonance as a tool for the characterization of magnetic fluids

A. Terheiden - M. Michaelsen - G. Dyker - C. Mayer

Institute of Chemistry, University of Duisburg, 47057 Duisburg, Germany

Abstract
Nuclear magnetic resonance spectroscopy is applied to magnetic fluids in order to provide information on particle magnetism, particle size and particle distribution under the influence of an external magnetic field. Instead of the particles themselves, the experiments focus on mobile spins in the fluid continuous phase under the influence of stray fields of the particles. The obtained spectra reflect a) the particle concentration, b) the particle magnetization, c) the particle agglomeration, and d) the shape of the sample container. A numeric algorithm for the simulation of NMR spectra has been developed that accounts for all these influences together with the lateral self diffusion of the spins in the fluid medium. Various examples are presented to demonstrate the applicability of the experimental techniques and the analysis of the resulting data. Figs 5, Refs 12.