Data for: Yerba Mate applications: magnetic response of powders and colloids of iron oxide nanoparticles coated with Ilex Paraguariensis derivatives
A wet-synthesis method was used to obtain iron oxide nanoparticle coated Yerba Mate. Nanoparticles have a core-shell structure with the iron oxide phase surrounded by an organic shell provided by the Yerba Mate extract. The Yerba Mate core width depends on the synthesis conditions. Powders and aqueous colloidal suspension of obtained nanoparticles were exhaustively characterized using several techniques. All of results together show that Yerba Mate extract shell mass to iron oxide core mass, mS / mc, could be increased up to 6.2 x 10-2, depending on the synthesis conditions. As a function of mS / mc the crystallite size of the nanoparticles decreased monotously from about 15 nm to 11 nm, while saturation magnetization Ms and coercive field Hc of powders decreased. Ms diminution was associated to increasing modification of core surface electronic states due to chemical bond of iron oxide to Yerba Mate extracts; on the other hand, coercivity reduction was modelled on the bases of the increasing interparticle separation and dipolar interaction weakening, which occurs as shell thickness grows. 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 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 based on a recently developed model was in agreement with the one performed for the coercive field behaviour.