## 3 Results and Discussion  
### Crystalline Structure  
The XRD method was used to obtain information about the phase transformations in the samples. The X-ray diffraction patterns of the as-prepared powders heated at 500 and 700 \({}^{\circ}\)C are shown in Figure 1a,b, respectively. They were compared to those of TiO\({}_{2}\) obtained from Ti(IV) butoxide. The XRD patterns of samples 90 TiO\({}_{2}\)/10 ZnO and TiO\({}_{2}\) heated at 500 \({}^{\circ}\)C show characteristic peaks at 20 values of 25.28, 37.8, and 48.05, which are related to the anatase phase (JCPDS 78-2486) (Figure 1a). Typical peaks of ZnO in the XRD pattern of this sample were not registered, while the XRD patterns of 10 TiO\({}_{2}\)/90 ZnO exhibited typical interplanar distances of wurtzite only (JCPDS 36-1451) [27]. The position of all the peaks did not change, confirming that there was no change in the crystal structure of the prepared material. It has been found that the combination of titania with zinc oxide leads to inhibition of the phase formation of the ZnO crystalline structure [28]. Given the similarity in ionic radii of Zn\({}^{2+}\) (60 pm) and Ti\({}^{4+}\) (60.5 pm), it can be posited that some Zn\({}^{2+}\) cations may integrate into the titania framework [29; 30].  
In the XRD patterns of the 90 TiO\({}_{2}\)/10 ZnO and TiO\({}_{2}\) samples subjected to heat treatment at 700 \({}^{\circ}\)C for 2 h, the characteristic diffraction bands at 27.4 and 36 of rutile (JCPDS 21-1279) were mainly observed (Figure 1b) [31]. However, diffractograms of the 10 TiO\({}_{2}\)/90 ZnO sample show reflections of wurtzite only. No other diffraction peaks were detected, which revealed that no impurities had formed in the TiO\({}_{2}\)/ZnO binary oxide system. As seen from the figure, the increase in temperature led to more narrow peaks, indicating an increase in the sample's crystallinity. The crystal size of all the investigated samples was calculated using [PERSON]'s equation, which was shown to be about 60 nm for the samples heated at 500, while at 700 \({}^{\circ}\)C, the particle sizes varied between 80 and 100 nm, with it being higher for 10 TiO\({}_{2}\)/90 ZnO (-100 nm). The XRD results clearly demonstrate that the crystalline structure of the resultant binary oxide system is influenced by the reagents' molar ratio. It was also observed that with a decrease in the TiO\({}_{2}\) content, the  
Figure 1: X-ray phase analysis of the samples annealed at 500 \({}^{\circ}\)C (**a**) and 700 \({}^{\circ}\)C (**b**).  
intensity of the characteristic anatase peak at 20 = 25.28 decreases. Similar results have been obtained by other authors [11,32]. Information on the sample surface was obtained by BET measurements. The investigated powders heated at 500 \({}^{\circ}\)C showed a specific surface value of about 45 m\({}^{2}\)/g, while at the same temperature, pure TiO\({}_{2}\) obtained from Ti(IV) butoxide exhibited a value of 68 m\({}^{2}\)/g. For the powders heat-treated at 700 \({}^{\circ}\)C, the surface values were as follows: \(\sim\)5 m\({}^{2}\)/g for both 90 TiO\({}_{2}\)/10 ZnO and pure TiO\({}_{2}\), while the 10 TiO\({}_{2}\)/90 ZnO sample exhibited a BET surface value of \(\sim\)2 m\({}^{2}\)/g.