Simulation of energy barrier distributions using real particle parameters and comparison with experimental obtained results

Abstract

In this work we compare previously measured energy barriers over the course of temperature with the results of simulations of the behaviour of the energy barriers. For the measurements the temperature dependent magnetorelaxation method (TMRX) was used. For the simulations of the energy barrier distribution we have used the real particles properties such as anisotropy and core size volume of the fractions of two magnetically fractionated ferrofluids. There is a good agreement between the simulated behaviour and the experimental obtained results. The influence of the particle volume concentration and agglomeration on the energy barrier distribution has been investigated. Finally the simulations confirm a previously published explanation for an experimentally obtained relaxation effect.

Stretched Exponential Change of Magnetic Weight of Magnetite Ferrofluid: Distribution of Energy Barrier for Agglomeration of Nanoparticles

“…As the exponent decreases, the distribution function becomes broader and the peak of the distribution function shifts to smaller k . These distribution functions fit relatively well (the regression coefficient R 2 ~ 0.9) with the log‐normal distribution function that is usually used in the studies of magnetic nanoparticles such as the distribution of particle sizes, anisotropy constants, and energy barriers of dipole–dipole interactions . Figure (b) shows the variation of the full width at half maximum [ Δ ( k τ)] and the peak position [( kτ ) max ] of the distribution function in the range of β between 0.25 and 1.…”