Authors: H. Dietsch, V. Malik, M. Reufer, P. Schurtenberger
Affilation: Fribourg Center fro Nanomaterials, FriMat, Switzerland
Pages: 226 - 229
Keywords: hematite, microrheology
Alpha-Fe2O3 (hematite) particles can be synthesized by forced hydrolysis of iron salts. The chosen iron salt dissolves and leads to a first crystalline structure called akaganeite (Beta-FeOOH), which, reorganized and combined with more iron precursor leads to the formation of hematite. Playing with physical and chemical means (concentration, pH, temperature, ionic force…) allows the control of size and shape of the obtained ferromagnetic particles. Here we will summarize our recent work on the synthesis of cubical single crystalline and of spindle-type anisotropic hematite particles. Spindle-type hematite particles can be obtained with axial ratios between 1 and 7. These particles can then be coated with a silica layer, allowing for the creation of a specific surface functionality for their incorporation in polymer matrices or simply for their stabilization in a given solvent. We will then demonstrate that a moderate magnetic field (12mT) is sufficient to orient our particles, and show how this can be used in order to prepare nanocomposites with tuneable and/or switchable properties or use them as nanoprobes to investigate local rheological properties of complex fluids.