## 3 Results  
### Studying the Properties of Nanocomposites Using Physico-Chemical Research Methods  
The phase state of the magnetic composite CoFe\({}_{2}\)O\({}_{4}\)/PVP was studied. Diffractograms were measured in the Bragg-Brentano geometry in the angle range of 20 = 15-100\({}^{\circ}\). The results of X-ray diffraction analysis of the obtained composites are presented in Table 1.  
According to the results of the X-ray phase analysis of unstabilized CoFe\({}_{2}\)O\({}_{4}\), in addition to the main phase CoFe\({}_{2}\)O\({}_{4}\) (spinel), Fe\({}_{2}\)O\({}_{3}\) (hematite) was found (Figure 1a), and the only crystalline phase present in the CoFe\({}_{2}\)O\({}_{4}\)/PVP sample was cobalt (II) ferrite with a cubic spinel structure with the space group Fd-3m (Figure 1b), PDF Number 010-74-6403. According to the results of the X-ray phase analysis, the unit cell parameters of CoFe\({}_{2}\)O\({}_{4}\) and CoFe\({}_{2}\)O\({}_{4}\)/PVP were 0.83880 and 0.83939 nm, respectively. The X-ray spectra of CoFe\({}_{2}\)O\({}_{4}\) nanoparticles show clearly defined diffraction peaks at 20 from 30.134, 35.494, 37.129, 43.383, 53.519, 57.052, and 62.651\({}^{\circ}\), corresponding to (220), (311), (222), (400), (422), (511), and (440); the planes and the results are in good agreement with JCPDS card No. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
** Composites** & **Phase** & **a, nm** & **c, nm** & **Concentration, \%** & **X-ray Density, g/cm\({}^{3}\)** & **Space Group** \\ \hline \multirow{4}{*}{CoFe\({}_{2}\)O\({}_{4}\)} & Fe\({}_{2}\)O\({}_{3}\) & \multirow{2}{*}{0.50367} & \multirow{2}{*}{1.37514} & \multirow{2}{*}{36.80} & \multirow{2}{*}{5.266} & \multirow{2}{*}{R-3 c} \\  & (hematite) & & & & & \\ \cline{1-1} \cline{3-5}  & CoFe\({}_{2}\)O\({}_{4}\) &  
22-1086. The sharp and clear peaks confirm that the CoFe\({}_{2}\)O\({}_{4}\) nanoparticles have a pure crystalline phase with a cubic spinel structure. The calculation of the crystal lattice parameters showed that, when cobalt is replaced with iron, the crystal lattice parameter increases, as a result of the fact that the radius of Co\({}^{2+}\) is greater than the radius of Fe\({}^{2+}\), and this is consistent with [PERSON]'s law, which states that there is a linear relationship between the crystal lattice parameter and the percentage of the element. It is calibrated with respect to Fe (KC: \(\alpha\)-iron). The structure and phase composition of a magnetic composite CoFe\({}_{2}\)O\({}_{4}\)/PVP were studied using Mossbauer spectroscopy (Figure 2; Tables 2 and 3). Figure 2 shows the Mossbauer spectra of the magnetic composites CoFe\({}_{2}\)O\({}_{4}\) and CoFe\({}_{2}\)O\({}_{4}\)/PVP. For CoFe\({}_{2}\)O\({}_{4}\):  
Absolute area of the experimental spectrum, w/s: 1.30657. The absolute area of the calculated spectrum, w/s: 1.30745 (100.07 % of exp.). Maximum of the exp. spectrum (effect), %: 4.527 +/\(-\) 0.113 (2.50 % of max.). \(\chi^{2}\) = 1.343. For CoFe\({}_{2}\)O\({}_{4}\)/PVP:  
Absolute area of the experimental spectrum, w/s: 2.70104. The absolute area of the calculated spectrum, w/s: 2.50534 (92.75% of the exp.). Maximum of the exp. spectrum (effect), %: 5.243 +/\(-\) 0.112 (2.13 % of max.). \(\chi^{2}\) = 2.704. Figure 1: Results of the X-ray diffraction of CoFe\({}_{2}\)O\({}_{4}\) (**a**) and CoFe\({}_{2}\)O\({}_{4}\)/PVP (**b**).