## 3 Results and Discussion
### Microstructure of the Zinc Titanate Precursor Powders calcined at Various Temperatures for 1 h  
The SEM microstructure of the zinc titanate precursor powders calcined at various temperatures for 1 h are shown in Figure 3. Figure 3(a) shows the morphology of the freeze-dried zinc titanate precursor powders without a dispersant agent or mineralizer agglomerates to the size of about 140 \(\pm\)70 \(\upmu\)m. The SEM micrographs in Figure 3(b) and (d) shows the zinc titanate precursor powders calcined at 600, 700 and 900 \({}^{\circ}\)C for 1 h, respectively. It can be seen that the agglomerated size of the particles increases as the calcination temperature rises from 600 to 900 \({}^{\circ}\)C. When calcined at 900 \({}^{\circ}\)C for 1 h, the size increases from 140 \(\pm\)70 \(\upmu\)m to 270 \(\pm\)170 \(\upmu\)m. Since the zinc titanate precursor powders were prepared through the wet-chemical routes, during this process, _i.e._, drying and/or subsequent steps, agglomeration can occur. During calcination, the most common type of agglomeration in the conventional powders was due to solid bonds that formed between the particles.  
The bright field (BF) and dark field (DF) TEM micrographs and the corresponding electron diffraction (ED) patterns of the freeze dried zinc titanate precursor powders calcined at 700 \({}^{\circ}\)C for 1 h are shown in Figure 4. Figure 4(a) shows the BF image, in which fine particles with size of about 5 nm and a larger particle with a length of 200 nm and width of 100 nm are observed. [PERSON] _et al_. [26] also reported the particle of TiO\({}_{2}\) is about 5 nm. Figure 4(a) shows that the larger particles, of ZnO which cause the contact area of ZnO with anatase TiO\({}_{2}\) to decrease, led to a decrease in the reaction of ZnO with anatase TiO\({}_{2}\), meaning that insufficient Zn\({}_{2}\)Ti\({}_{3}\)O\({}_{8}\) was produced. Figure 4(b),(c) shows the DF images of the fine and larger particles in Figure 4(a). In addition, Figure 4(d),(e) shows the ED patterns of the particles in Figure 3(b),(c), respectively. The ED pattern of Figure 4(d) corresponds to the phases of ZnTiO\({}_{3}\) and rutile TiO\({}_{2}\). On the other hand, the ED pattern of Figure 4(e) corresponds to ZnO.  
Figure 2: X-ray diffraction (XRD) patterns of ZnTiO\({}_{3}\) precipitates calcined at various temperatures for 1 h: (**a**) before calcination, (**b**) calcined at 600 \({}^{\circ}\)C, (**c**) 700 \({}^{\circ}\)C, and (**d**) 900 \({}^{\circ}\)C.  
Figure 5(a),(b) shows the BF and DF images of the freeze dried zinc titanate precursor powders calcined at 900\({}^{\circ}\)C for 1 h, revealing that two kinds morphology coexist in the sample. One is the fine particles with a size of about 50 nm, and the other one is belt-shape particles with a length of 200 nm and width of 50 nm. The ED pattern of the Figure 5(c) belt-shaped and fine particles correspond to ZnTiO\({}_{3}\) with a zone axis (ZA) of [110]. Figure 5(d),(e) shows the BF and DF images of the fine particles with the size of about 38 \(\pm\) 18 \(\upmu\)m. The ED pattern of Figure 5(f) corresponds to ZnTiO\({}_{3}\) with the ZA of [i\(\bar{\mathrm{n}}\)i].