Characterization of cobalt ferrite nanoparticles obtained by various synthesis methods and comparison with the Raman spectra of other ferrites and some cubic oxide spinels

Single phase cobalt ferrite (CoFe2O4) with nanoparticles of similar sizes (15.7-19 nm) was obtained by different synthesis methods: coprecipitation, ultrasonically assisted coprecipitation, coprecipitation followed by mechanochemical treatment, microemulsion and microwave assisted hydrothermal synthesis. The obtained CoFe2O4 samples have been studied using a variety of characterization techniques: X-ray diffraction (XRD), Raman spectroscopy, far infrared (FIR) reflectivity and attenuated total reflectance (ATR) in combination with Fourier-transform infrared (FTIR) spectroscopy in mid IR spectra. Different methods of synthesis produced nanoparticles with different lattice constants, internal stresses and different cation inversion values. This is confirmed in the subtle changes in the Raman and IR spectra of different CoFe2O4 nano-powders. The Raman spectra of CoFe2O4 were compared with the spectra of other ferrites and some cubic oxide spinels in an attempt to evaluate the contribution of tetrahedral and octahedral oscillations in certain Raman modes.