Yerba Mate applications: Magnetic response of powders and colloids of iron oxide nanoparticles coated with Ilex paraguariensis derivatives

Differences between the particle core mean size obtained with TEM, SAXS, XRD and magnetic measurements are observed. The fact that magnetic size was smaller than particle and crystallite sizes was attributed to the existence of intense dipolar interactions. It was found that low field susceptibility in a colloid sample was about 2.5 times that of the powder specimen, a result that shows that demagnetizing effects prevail in the powder specimen, while they may be absent in the colloid due to the larger interparticle mean separation expected in the latter. Analysis of powder and colloid susceptibility was done based on a recently developed model was in agreement with the one performed for the coercive field behaviour.