Magnetic properties of polypyrrole-coated iron oxide nanoparticles

Abstract

Iron oxide nanoparticles were prepared by sol -gel process. In-situ polymerization of pyrrole monomer in the presence of oxygen in iron oxide -ethanol suspension resulted in a iron-oxide polypyrrole nanocomposite. The structure and magnetic properties of the nanocomposites with varying pyrrole concentrations are investigated. The X-Ray diffraction studies indicate the presence of γ − F e 2 O 3 phase for the concentrations investigated. FTIR studies confirm the presence of polypyrrole. The TEM studies show agglomeration in uncoated samples and in samples with a lower concentration of polypyrrole. Agglomeration is much reduced for samples coated with higher concentration of polypyrrole. The ac susceptibility measurements performed in the temperature range 77 -300 K shows the presence of blocking, indicating the superparamagnetic phase. The blocking temperature is found to depend on the pyrrole concentration. Monte Carlo studies for an array of polydispersed single domain magnetic particles, based on an interacting random anisotropy model were also carried out and the blocking temperatures obtained from the simulation of the ZFC-FC magnetization compares favorably with experimental results.

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