## 3 Results and Discussion
### Mossbauer, EPR and Magnetization Curves  
The Mossbauer spectroscopy studies are performed to obtain the chemical environments of the iron on the samples [22; 35; 36]. Mossbauer spectrum of Fe depicts the typical shape of Fe\({}_{3}\)O\({}_{4}\) with four sextets, e.g., S1, S2, S3 and S4 (Figure 5a). The S1 corresponds to the hyperfine magnetic field of 47.42 T and \(\delta\) = 0.44 mm\(\cdot\)s\({}^{-1}\) while S2 has B\({}_{\rm HF}\) of 47.08 T and \(\delta\) = 0.15 mm\(\cdot\)s\({}^{-1}\) (Table 3). These kinds of sextets are typical of Fe\({}_{3}\)O\({}_{4}\) cubic spinel structure with [Fe\({}^{3+}\)]\({}^{\rm tetra}\) [Fe\({}^{2+}\)Fe\({}^{3+}\)]\({}^{\rm oct}\)O\({}_{4}\), in agreement with findings on XRD and Raman. The corresponding average parameter for S1 and S2 accounts to 54.7% of the total amount of Fe\({}_{3}\)O\({}_{4}\) relative abundance. Indeed, S1 sextet suggests that the Fe\({}^{3+}\) occupies tetrahedral sites whereas the S2 one corresponds to the Fe\({}^{2+}\)/Fe\({}^{3+}\) in tetrahedral and octahedral sites in non-stoichiometric magnetite [36; 37; 38]. The possibility of maghemite presence cannot be ruled out, since the \({}^{57}\)Fe hyperfine parameters, isomer shift and quadrupole splitting calculated from the two doublets are close to those of Fe\({}_{3}\)O\({}_{4}\). This confirms the XRD results. Also, it should be underlined that the Mossbauer parameters in Fe sample are a rather difficult to exclude the possibility of \(\alpha\)-Fe\({}_{2}\)O\({}_{3}\). The two other sextets namely S3 and S4 have hyperfine field of 38.46 and 41.49 T matching well with goethite (\(\alpha\)-FeOOH) phase [38]. Accordingly, the parameters of \(\Delta\) = -0.54 and 0.07 mm\(\cdot\)s\({}^{-1}\) for S3 are assigned to Fe\({}^{3+}\) ions of goethite, which represents 26.4% of the relative abundance (Table 3). Figure 5: Fitted room temperature Mössbauer spectra of the samples studied (**a**) Fe, (**b**) Fe/C and (**c**) Fe/FeC. The letters S and D represent the sextet and doublets of the curves. The FeC spectrum is deconvoluted into a doublet and one sextet, as presented in Figure 5b. The doublet with the parameters such as \(\Delta=0.74\) mm\(\cdot\)s\({}^{-1}\), \(\delta=0.34\) mm\(\cdot\)s\({}^{-1}\) and R.A of 62.3% are typical of superparamagnetic particles of magnetite particles, in accordance to other reports as found in the literature [39]. The remaining relative abundance of ca 37.4% is associated with the sextet possessing the resolved hyperfine parameters of B\({}_{\rm HF}=46.74\) T. \(\Delta=-0.27\) mm\(\cdot\)s\({}^{-1}\) and \(\delta=0.31\) mm\(\cdot\)s\({}^{-1}\). Thus, carbon content does not change magnetite phase. Only, oxidation states of Fe\({}^{2+}\) to Fe\({}^{3+}\) are likely ascribing in maghemite phase for FeC composite. Similarity, the appearance of one fitted doublet and sextet in the Fe/FeC spectrum (Figure 5c) determines the magnetic structure is composed of both Fe\({}^{2+}\) and Fe\({}^{3+}\) from magnetite and maghemite. The hyperfine parameter of the doublet is the same as that of the FeC with relative abundance, e.g., RA of 60.2% and the remaining 39.8% for the sextet. This implies that the super-paramagnetic spin relaxation of the particles may take place. Thus, the introduction of additional iron phases in FeC may lead to formation of maghemite coating. EPR spectroscopic studies of the solids are performed to directly identify all iron phases. The two broad signals of the X-band electron magnetic resonance spectra are clearly visible for all of samples (Figure 6a). The line shapes on EPR spectrum for Fe sample are broader and more asymmetric in comparison with other samples indicating a ferromagnetic resonance. Additionally, a main signal at around 1500 Oe has g-factor of 2.2, which suggest similar distributions of Fe\({}^{3+}\) species in the solid. These