Investigations on magnetic particles prepared by cyclic growth

Magnetic iron oxide nanoparticles are promising tools for medical applications like hyperthermia or magnetic drug targeting. The relevant properties in these applications strongly depend on particle size and size distribution. In order to investigate the influence of mean size as well as size distribution, iron oxide powders from particles by a cyclic method based on “conventional” precipitation from Fe-salt solution were prepared. Increasing mean particle size with increasing number of cycles is confirmed by XRD. Magnetic parameters of the saturation hysteresis loop, hysteresis losses calculated from minor loops and switching field distributions are shown. A fractionation experiment on a fluid sample of particles prepared by 3 cycles was carried out in order to improve the hysteresis losses.

Research Highlights
► Cyclic growth allows to larger growth and magnetically harder iron oxide particles.
► Multicycle samples still contain a fraction of superparamagnetic particles.
► The mean switching field increases and its distribution width slightly decreases with number of cycles.
► At low fields there is a weak influence of number of cycles on hysteresis losses.
► The losses in this range could be increased by magnetic fractionation.