## 3 Results and Discussion
### Structural and Surface Properties  
The difference in nucleation and growth of both coatings prepared by GIMS was also identified on the basis of SEM images of the surface and cross-section. For the measurements, samples as deposited and annealed at 200 \({}^{\circ}\)C, 400 \({}^{\circ}\)C, and 600 \({}^{\circ}\)C were selected as they demonstrated the most significant changes in optical parameters. SEM studies have revealed that, in both cases, all films were homogeneous and densely packed. In the case of TiOx films deposited under oxygen-rich conditions (ORC), the columnar microstructure can be distinguished (Figure 5). As can be seen, annealing did not cause strong microstructural changes until a temperature of 600 \({}^{\circ}\)C was reached (Figure 5d). It should be noted that the film after deposition and those annealed at a lower temperature were made of finer columns (Figure 5a-c). This can be seen based on the analysis of their surface shape. A significant change occurred after annealing at 600 \({}^{\circ}\)C, which resulted in a strong increase in the size of the columns; however, this did not cause other defects in the microstructure, such as cracks and voids between adjacent columns. The columnar character of Ti-based oxide films, as well as its growth with increasing annealing temperature, can be considered as quite typical and expected, as demonstrated in earlier studies [19,31]. However, it must be noted that such a densely packed microstructure is characteristic of TiOx coatings obtained from GIMS \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**TiOx\({}^{\text{ODC}}\) Coating** & **T\({}_{\text{A}}\) = 550 nm** & **R\({}_{\text{A}}\) = 550 nm** & **\(\lambda_{\text{cut-off}}\)** & **E\({}_{\text{g}}^{\text{opt}}\)** & **E\({}_{\text{u}}\)** \\ \hline as deposited & & 0.0 & 14.3 & – & – & – \\ \hline  & 100 \({}^{\circ}\)C & 0.0 & 16.2 & – & – & – \\  & 200 \({}^{\circ}\)C & 13.4 & 20.5 & 449.5 & 0.70 & 0.77 \\ annealed at: & 300 \({}^{\circ}\)C & 7.0 & 28.1 & 544.0 & 0.50 & 0.37 \\  & 400 \({}^{\circ}\)C & 6.3 & 21.6 & 537.0 & 0.49 & 0.43 \\  & 600 \({}^{\circ}\)C & 5.3 & 20.3 & 547.7 & 0.44 & 0.40 \\  & 800 \({}^{\circ}\)C & 4.2 & 19.6 & 549.7 & 0.30 & 0.47 \\ \hline \hline \end{tabular} Designations: T\({}_{\text{A}}\)—transparency level, R\({}_{\text{A}}\)—reflection level, \(\lambda_{\text{cut-off}}\)—absorption edge, E\({}_{\text{g}}^{\text{opt}}\)—optical band gap, E\({}_{\text{u}}\)—Urbach energy.  
\end{table} 
Table 2: Optical properties of the TiOx coating deposited under ODC. Figure 4: Determination of: (**a**) optical band gap (E\({}_{\text{g}}^{\text{opt}}\)), (**b**) Urbach energy (E\({}_{\text{u}}\)), (**c**) absorption edge (\(\lambda_{\text{cut-off}}\)) of TiOx\({}^{\text{ODC}}\) films as deposited under oxygen-deficient conditions, and (**d**) the calculated values of these parameters as a function of the annealing temperature. processes [25; 32]. A completely different nature of the microstructure was obtained in the case of the sputtering process carried out under the condition of oxygen deficiency. The more metallic character of the layer, due to a low amount of oxygen, resulted in a densely packed and grainy morphology of TiOX\({}^{\text{ODC}}\) (Figure 6). Additional annealing resulted in an increase in grain sizes from ca. 20 to 50 nm. However, there is no structural order that extends beyond individual grains even after annealing at 600 \({}^{\circ}\)C. Furthermore, it is not easy to distinguish individual grains and their limits, especially for films other than the one annealed at 600 \({}^{\circ}\)C, which indicates their amorphous form [32]. The influence of additional annealing on the structure of coatings prepared by GIMS processes was also determined on the basis of GIXRD studies. The patterns collected for the TiOX\({}^{\text{ORC}}\) and TiOX\({}^{\text{ODC}}\) thin films are shown in Figure 7. Both films as deposited were found to be amorphous.