Control of the Magnetism of Iron Oxide Nanoparticles By Growth Parameters within Nanostructured Silicon

In the frame of this work nanostructured silicon is used as template for the deposition of iron oxide within the pores. The aim is to fabricate a nanocomposite which is appropriate to be used as vehicle for magnetic field guided drug delivery. For this reason several preconditions have to be fulfilled, e.g. no magnetic remanence at room temperature and biocompatibility of the used materials. The latter one has been evidenced by different authors before (1, 2, 3). Concerning the adjustability of the magnetic properties of the system the filling of the porous silicon with iron oxide nanoparticles has been elucidated in detail and the growth of the iron oxide structures within the pores has been investigated. The growth mechanism strongly depends on the electrolyte composition as well as on the applied potentiostatic conditions. The magnetic properties, especially the transition temperature between superparamagnetic behavior and blocked state (T_B) of the nanocomposite can be controlled by the filling procedure. T_B shifts to higher temperatures with increasing magnetic coupling between the particles. Dependent on the packing density as well as on the size of the particles within the pores the magnetic interactions can be modified and thus the blocking temperature can be tuned. These investigations have been carried out for particle sizes between 4 nm and 12 nm. An optimization of the magnetization (high filling density as possible) and its correlation with the blocking temperature has been carried out. An assessment of the iron oxide deposition dependent on the template and the chemical parameters as well as of the magnetic properties in dependence on the particle size, inter-particle distance and template morphology of the nanocomposite will be presented.  

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