Mössbauer spectroscopy study of nanosized spinel CoFe2O4 ferrite obtained during coprecipitation followed by mechanochemical treatment

The powdery cobalt ferrite (CoFe2O4) is prepared by coprecipitation followed by mechanochemical synthesis in a planetary ball mill. Obtained nanomaterial has 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. The investigated CoFe2O4 nanomaterial showed a typical XRD pattern of cubic spinel. In the Raman and IR spectra are observed all of first-order Raman and IR active modes. Weak sub-bands activated by structure disorder are seen also. Since nano-CoFe2O4 is macroscopically cubic, its main Raman and IR modes are assigned as in normal cubic spinel. Raman spectrum is fitted with 8 Lorentzian peaks. It is observed that the value of x 0.58 obtained from Raman spectrum, is in good agreement with the value obtained by XRD-structural analysis (0.51). To analyze the IR spectra, we used Decoupled Plasmon - Phonon (DPP) model of the complex dielectric function. Measurement of magnetization in the range of magnetic fields H>>Hc enable the calculation of the anisotropy coefficient K1 = 4.02·105 J cm-3, which is very high in cobalt ferrite. The 57Fe-Mössbauer spectrum of the CoFe2O4 sample was measured at room temperature in ± 12 mm s-1 Doppler velocity range. The 57Fe-Mössbauer spectrum of the CoFe2O4 sample was fitted with the extended Voigt-based fitting method.