Synthesis and characterisation of metal oxides nanoparticles entrapped in cyclodextrin Original Research Article

A new technique to prepare very small metal oxide (γ-Fe2O3, NiO and CoO) magnetic nanoparticles is presented. Nanoparticles are prepared by addition of NaOH to a ferrous chloride solution in the presence of γ-cyclodextrin and once formed are entrapped in the pseudo-single crystals of the oligosaccharide. The resulting crystals give diffraction pattern which looks like those of pure γ-cyclodextrin crystals. Evidences of nanosized particles embedded in the organic crystals were obtained by HREM. The magnetic properties, investigated by ZFC-FC magnetisations, hysteresis loops and ac susceptibility measurements, deviate from those predicted on the basis of the classic single domain particles model due to the complex properties of the surface which for such small sizes, plays the major role in the total magnetic behaviour.