Magnetosensitive Nanocomposite Fe₃O₄/Al₂O₃/C Synthesis and Properties

The processes of carbonization of sucrose-containing coatings on the surface of single-domain magnetite and magnetosensitive nanocomposite (MNC) Fe₃O₄/Al₂O₃ are studied. The MNC with a carbon surface is synthesized by the method of low-temperature pyrolysis of carbohydrates. As revealed, the used heat-treatment mode does not lead to deterioration of the magnetic characteristics of magnetite under the condition of preliminary creation of a protective layer of alumina on its surface. Differential thermal analysis (DTA) in combination with differential thermogravimetric analysis (DTGA) and programmed temperature-desorption mass spectrometry show that the carbonization of sucrose under these conditions is complete. The shape and dimensions of the Fe₃O₄, Fe₃O₄/Al₂O₃ and Fe₃O₄/Al₂O₃/C MNCs are investigated by the TEM method. As established, the values of the specific saturation magnetization of MNCs are consistent with the corresponding changes in the mass fraction of magnetite in the Fe₃O₄/Al₂O₃ and Fe₃O₄/Al₂O₃/C structures. The results of TEM studies and magnetic measurements indicate the formation of the Fe₃O₄/Al₂O₃ and Fe₃O₄/Al₂O₃/C MNCs by the core-shell type. Methylene blue is used to study the adsorption activity of the Fe₃O₄/Al₂O₃/C MNC surface. The results of the work can be used in the development of new magnetically controlled adsorption materials for medical-biological purposes.