Size Dependence of the Magnetic Properties in Superparamagnetic Zinc-Ferrite Nanoparticles

Size Dependence of the Magnetic Properties in Superparamagnetic Zinc-Ferrite Nanoparticles

In order to investigate the size dependence of the magnetic properties in superparamagnetic nanoparticles, we synthesized four different-sized superparamagnetic zinc-ferrite nanoparticles between 9.8 and 13.4 nm and investigated them by using X-ray diffractometry and superconducting quantum interference device (SQUID) magnetometry. The lattice constant for each sample was slightly bigger than that of the zinc-ferrite bulk and tended to increase with decreasing particle size of the sample. As the particle size decreased, the magnetization and the blocking temperature, suggesting the appearance of superparamagnetic relaxation, also increased. These tendencies may be ascribed to the surface effect, the size effect and the variation of the site distribution with decreasing particle size in nanoparticle systems.

In order to investigate the size dependence of the magnetic properties in superparamagnetic nanoparticles, we synthesized four different-sized superparamagnetic zinc-ferrite nanoparticles between 9.8 and 13.4 nm and investigated them by using X-ray diffractometry and superconducting quantum interference device (SQUID) magnetometry. The lattice constant for each sample was slightly bigger than that of the zinc-ferrite bulk and tended to increase with decreasing particle size of the sample. As the particle size decreased, the magnetization and the blocking temperature, suggesting the appearance of superparamagnetic relaxation, also increased. These tendencies may be ascribed to the surface effect, the size effect and the variation of the site distribution with decreasing particle size in nanoparticle systems.