## 3 Results and Discussion
### Mossbauer, EPR and Magnetization Curves
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Samples**} & \multicolumn{4}{c}{**Electric Quadrupole and Isomer Shift**} \\ \cline{2-5}  & **B\({}_{\rm HF}\) (T)** & \(\Delta\) **(mm/s)** & \(\delta\) **(mm/s)** & **R.A. (\%)** \\ \hline Fe (S1) & 47.42 & \(-0.01\) & 0.44 & 30.2 \\ Fe (S2) & 47.09 & \(-0.18\) & 0.15 & 24.5 \\ Fe (S3) & 38.46 & \(-0.54\) & 0.07 & 26.4 \\ Fe (S4) & 41.60 & 0.13 & 1.02 & 18.8 \\ Fe/FeC (S1) & 46.83 & 0.08 & 0.44 & 39.8 \\ Fe/FeC (D) & – & 0.73 & 0.33 & 60.2 \\ FeC (S1) & 46.74 & \(-0.27\) & 0.31 & 37.4 \\ FeC (D) & – & 0.74 & 0.34 & 62.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Mössbauer parameters obtained from refinements of the spectra at 77 K. Electric quadrupole splitting (\(\Delta\)), isomer shift (\(\delta\)), hyperfine magnetic field (B\({}_{\rm HF}\)) and Relative spectral area (R.A) parameters of the Fe-containing samples. The letter S represents the sextets in the samples. Figure 6: (a) EPR spectra and (b) Magnetic saturation hysteresis loops of the samples studied. features are frequently observed in other Fe-based samples mainly in hematite phase, as described elsewhere [40; 41]. Indeed, the features of the spectra are also typical of cubic magnetocrystalline anisotropy in solids such as magnetite. In accordance with the literature reports, the spectra display the typical cubic magnetocrystalline anisotropy for magnetite-based solids [42; 43]. The lowest signal at around 4700 Oe depicts g = 4.0 suggesting the paramagnetic resonance of isolated Fe\({}^{3+}\) with rhombic symmetry, in which the ions are located in tetrahedral FeO\({}_{4}\) and/or octahedral FeO\({}_{6}\) local and Fe\({}^{2+}\) species [40; 41; 42]. It is important to note that the EPR spectra line shapes of the Fe/FeC and FeC composites are strikingly similar with narrow signals, compared to that of Fe sample. Moreover, the first signal experiences a shift to high values of magnetic fields regions whereas the second one shifts to low regions. This means that the asymmetry ratio values are distinct for all samples. Also, it could be indicative of the negative first order cubic magnetocrystalline anisotropy, in agreement with the literate [43]. This is more evident for Fe/FeC than in FeC that possesses the lowest magnetocrystalline anisotropy field. Although the EPR spectra of magnetite are still controversial due to the strong absorption of microwave in region, the possible certainties in the assignments are confirmed by the Mossbauer spectroscopy. To further understand the nature of the Fe species, the magnetic properties of the solids are obtained by the Vibrating sample magnetometer (VSM). Data of magnetic hysteresis loops (MS) are taken at room temperature, as depicted in Figure 6b. Fe sample has at approximately 58 emu/g, which is much lower than that of the reported value for pristine Fe\({}_{3}\)O\({}_{4}\), e.g., 92 emu/g [44]. Considering that the existence of non-collinear spins at the surface of Fe\({}_{3}\)O\({}_{4}\) particles is likely to occur, this might justify the observed low hysteresis value, as previously reported in the literature [36]. The later observations can be associated with the maghemite, hematite and goethite as minority phases in Fe sample. These assumptions are in agreement with coercive field (\(H_{\rm c}\)) value for magnetic particles [34; 36]. The hysteresis loops and coercive field of the Fe-based composites are reduced by approximately 30%. On the basis of XRD, Raman and Mossbauer data, the magnetic properties can attribute to carbon coating on the magnetic particles. The findings also state that either structural/magnetic transition or anomalous temperature dependence of the magnetocrystalline anisotropy as well as the decreased size of the magnetic structure may cause these behaviors [36].