Morphological investigation of monodispersed manganese ferrite nanoparticles by the impedance measurement

摘要

Particle size distributions in manganese ferrite ferrofluids are analyzed based on ac susceptibility measurements. The frequency dependence of the complex susceptibility, χ"(ω), of the ferrofluid was measured by the slit-toroid technique. The sample exhibited frequency response due to Neel's rotational relaxation, from which the particle size was estimated. A modified log-normal distribution is used for fitting the experimental results, which allows proper account of the narrow distributions. The calculated average particle size is in good agreement with transmission electron microscopy result.