Crystal structures and magnetic properties of polyethylene glycol/polyacrylamide encapsulated CoCuFe4O8 ferrite nanoparticles

Polymer-inorganic nanocomposites with systematized structure provide a novel composite material having complementary between the polymer and inorganic materials. A new CoCuFe4O8 spinel ferrite was prepared by a modified citrate auto combustion technique. The formation of the core-shell structure by coating CoCuFe4O8 nanoparticles (NPs) with Polyethylene glycol (PEG) or Polyacrylamide (PAM) was successfully proceeding. The X-ray diffraction analysis shows that the prepared sample crystallizes in a cubic crystal structure with the Fd3m space group. The structural changes are elucidated via diametrical size, lattice parameter, dislocation density and strain. The obtained data reveals that after coating with PEG/PAM the crystallite size of CoCuFe4O8 spinel ferrite nanoparticles decreases while, the dislocation density increases. The dislocation density provides more energy-friendly locations for nucleation, consequently, the crystallinity deteriorates and the crystal grains become finer. High-Resolution Transmission Electron Microscopy (HRTEM) images ratify that the spinel nanoparticles are embedded in the PEG/PAM matrix forming the core-shell structure. The measurements of the magnetic hysteresis loops assure that all prepared samples exhibit a hard ferrite nature with a coercivity ranging from 1525 to 1512 Oe. The decrease of the magnetic parameters of CoCuFe4O8/PEG-PAM can be explained on the basis of the contribution of the non-magnetic coating layer to the total magnetization. The total magnetic behavior of the nanocomposites can be tuned and tailored depending on the coating layers. Based on the obtained data, the formulated CoCuFe4O8 decorated with PEG-PAM can be recognized as a promising functional material for applications in biomedicine. The enhanced magnetic properties make CoCuFe4O8/PEG-PAM a fitting candidate in the high-density recording.