## 3 Results
### Ceramic SiC and SiC/\(\mathrm{C_{f}}\) Microspheres
The recorded maximum weight loss was taken as the content of free carbon, Table 2. The total carbon (C\({}_{\rm total}\)) content was determined by combustion of ceramic microspheres in oxygen in a tube furnace at 1200-1300 \({}^{\circ}\)C using the coulometric detection method, Table 2. The C\({}_{\rm f}\) content was calculated from the mass balance assuming that the sample contains only SiC, SiO\({}_{2}\) and C\({}_{\rm f}\), Table 2. Additionally, the elemental composition of the ceramic microspheres was confirmed by Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy, SEM/EDS, (s.i. Table S2 and Figure S3). The obtained results are consistent with the TGA analysis and show that only ceramic microspheres were obtained from the aromatic carbon-rich siloxane particles, which are formed when the \(w/w\) ratio of DVB to PHMS was above 0.48, contain a significant amount of the free carbon, Table 2.0 The aromatic carbon is also visible in the \({}^{13}\)C NMR HPDec/MAS spectra, Table 2.1 The spectra show a broad signal of sp\({}^{2}\) carbon-centered at about 110 ppm belonging mostly to C\({}_{\rm f}\) and a sharp signal at 20 ppm of sp\({}^{3}\) carbon originating mainly  
Table 2.2 Effect of DVB proportion on free carbon content from (\(\Delta\)) elemental analysis and (\(\square\)) TGA weight loss and (\(\bullet\)) ceramic yield of ceramic microspheres. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **D Position** & **G Position** & & \\  & **(FWHM)** & **(FWHM)** & **I(D)/I(G)** & **L\({}_{\rm a}\)(nm)** \\  & **cm\({}^{-1}\)** & **cm\({}^{-1}\)** & & **(\(\times\)= 488)** \\ \hline \multirow{2}{*}{A-4} & 1356 & 1590 & \multirow{2}{*}{1.55} & \multirow{2}{*}{2.8} \\  & (55) & (46) & & \\ \hline \multirow{2}{*}{A-5} & 1356 & 1588 & \multirow{2}{*}{1.18} & \multirow{2}{*}{3.4} \\  & (46) & (40) & & \\ \hline \multirow{2}{*}{A-6} & 1356 & 1589 & \multirow{2}{*}{1.47} & \multirow{2}{*}{3.0} \\  & (52) & (43) & & \\ \hline \multirow{2}{*}{A-7} & 1350 & 1593 & \multirow{2}{*}{2.04} & \multirow{2}{*}{2.2} \\  & (53) & (57) & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Results of Raman studies of SiC/C\({}_{\rm f}\) microspheres. from SiC. The sp\({}^{2}\) signal is enhanced by the NOE effect [46] thus the results have only qualitative meaning. It is worth mentioning that polysiloxane microspheres obtained in our standard method [36] using 1,3-divinyltetramethyldisiloxane as crosslinker (Sample B-1) was subjected to the ceramization under the same conditions as other samples. The analysis showed that the ceramic SiC microspheres obtained in this way did not contain any C\({}_{\text{f}}\) and the yield of the ceramization was very low, Table 2. These microspheres retained spherical shape and exhibited a high macroporosity, as it is discussed below. The \({}^{29}\)Si MAS NMR spectra of the ceramic microspheres shown in Figure 6 confirm the presence of SiC. The signal corresponding to SiO\({}_{2}\) at \(-108\) ppm was not detected. Signals of other oxygen-containing silicon tetrahedra were not detected either. These suggest that residual oxygen in the ceramic microspheres should be below 2 w%, which was confirmed by elemental analysis, Table 2. The only silicon species visible in these spectra are those originating from silicon carbide. It exists mainly in the crystalline form of \(\beta\)-SiC, which is confirmed by the presence of a sharp signal at \(-19\) ppm. Broader signals ranging from \(-23\) to \(-27\) ppm can be attributed to the amorphous form of silicon carbide and other crystalline SiC polytypes. Further information about the structure of the silicon carbide phase is provided by X-ray diffraction studies. The diffractograms for all samples are similar to each other and indicate the high crystallinity of the silicon carbide phase which appears as a \(\beta\)-SiC crystal structure.