Magnetic size determination for interacting fine particle systems

Interparticle interactions play an important role in the magnetic response of a magnetic fluid. Using the Monte Carlo technique, the effects of interactions on the determination of magnetic particle size distribution parameters are investigated. It is shown that these interactions introduce a significant error in the value obtained for the standard deviation, whilst the effect on the median diameter is less pronounced. Using an approach based on the representation of interactions by means of a thermodynamic ordering temperature, expressions are derived which enable the distribution parameters of a weakly interacting system of particles to be determined. These equations are applied to experimental data for two different types of colloidal dispersion, in each case giving improved results.