Core–shell structure in copper ferrite–polyaniline nanocomposite: Confirmation by laser Raman spectra

Abstract

Laser Raman spectroscopy was used to investigate the presence of core–shell structure in copper ferrite–polyaniline nanocomposites prepared by in situ polymerization method. Laser beams with two excitation powers, 0.3mW and 3mW, were employed to study the ferrite–polyaniline interaction and its changes by the laser induced heating effects. Low energy Raman spectra distinctly displayed polyaniline bands only without bands for CuFe2O4 in all the nanocomposites. This observation attributes polyaniline shell over the CuFe2O4 core particle, since the low energy was not sufficient for the beam to penetrate the polyaniline shell. However, with higher incident energy due to the induced heating effect, there was disturbance of polyaniline shell and the Raman frequencies were shifted depending on the shell thickness. Raman spectra of copper ferrite–polyaniline nanocomposites recorded using higher energy beam were consistent with the low energy Raman spectra of polyaniline samples annealed at three different temperatures of 200, 300 and 400°C respectively for 2h. High-resolution scanning electron microscope study also supports the formation of core–shell structure. It revealed that the average particle size increases with increase of shell thicknesses.