## 3 Results  
The microstructure of biocearamics composed of silica and titanium oxide with various concentrations of titanium oxide soaking in SBF for 0 and 7 days are shown in Figure 1. At 0 days of soaking in SBF, the size of the biocearamic particles, though not very evident, become bigger from BG_Ti25 to BG_Ti00. At 7 days of soaking in SBF, it is obvious that mineral deposits on the sample surface and the particles also become bigger from BG_Ti25 to BG_Ti00. The particle also formed a cluster-like deposition on the BG_Ti00 surface. It showed the various microstructures on the sample surface after soaking in SBF for 7 days. Table 1 shows that the atomic ratio of biocearamics composed of silica and titanium oxide with various concentrations of titanium oxide soaking in SBF for 7 days. The atomic ratio of various elements was described as follows. The Si atomic ratio of all the samples decreased after soaking for 7 days. Moreover, the Si atomic ratio decreased more drastically after 7 days if samples originally contained a higher Si atomic ratio. This showed the solubility of silica in the samples. For BG_Ti25, BG_Ti50, and BG_Ti75, the Ca atomic ratio increased after soaking for 7 days. However, Ca atomic ratio of BG_Ti100 decreased after soaking for 7 days. This showed that BG_Ti25, BG_Ti50, and BG_Ti75 can form calcium salt on their surface but BG_Ti100 can be the Ca ion provider. All of the samples' P atomic ratios increased after soaking for 7 days. This showed that all samples can form the phosphate compound on their surface. In all samples, the Ti atomic ratio increased drastically after soaking for 7 days. The main reason was that the titanium oxide was not soluble in water. It is worth noting that  
the Si/Ti ratios were very high, and the Si/Ti ratio at 0 days decreased going from BG_Ti25 to BG_Ti00. However, the Si/Ti ratio decreased drastically after soaking in SBF for 7 days. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{
\begin{tabular}{c} **S soaking** \\ **Periods** \\ \end{tabular} } & \multirow{2}{*}{**Samples**} & \multicolumn{4}{c}{**At. \%**} & \multirow{2}{*}{**Ca/P**} & **Si/Ti** \\ \cline{3-3} \cline{5-10}  & & **Si** & **O** & **Ca** & **P** & **Ti** & **Ratio** & **Ratio** \\ \hline \multirow{4}{*}{0 day} & BG\_Ti25 & 35.69 & 57.62 & 8.70 & 1.73 & 0.24 & 5.03 & 149 \\  & BG\_Ti50 & 25.30 & 66.39 & 6.90 & 1.32 & 0.10 & 5.23 & 253 \\  & BG\_Ti75 & 26.71 & 65.59 & 6.23 & 1.21 & 0.27 & 5.15 & 99 \\  & BG\_Ti100 1 & 25.74 & 60.20 & 11.97 & 1.61 & 0.47 & 7.43 & 55 \\ \hline \multirow{4}{*}{7 days} & BG\_Ti25 & 11.21 & 64.41 & 12.83 & 9.33 & 3.22 & 1.38 & 3 \\  & BG\_Ti50 & 15.79 & 67.54 & 8.97 & 3.94 & 3.76 & 2.28 & 4 \\ \cline{1-1}  & BG\_Ti75 & 15.58 & 62.68 & 15.98 & 2.32 & 3.44 & 6.89 & 5 \\ \cline{1-1}  & BG\_Ti100 1 & 21.89 & 67.98 & 5.70 & 2.27 & 2.16 & 2.51 & 10 \\ \hline \hline \end{tabular}  
* The raw materials of Ti100 were prepared with a Si/Ti ratio of 10:1.  
\end{table} 
Table 1: The atomic ratio of biocearamics composed of silica and titanium oxide with various concentrations of titanium oxide after soaking in SBF for 7 days. Figure 1: The microstructures of biocearamics composed of silica and titanium oxide with various concentrations of titanium oxide soaking in simulated body fluid (SBF) for **(a)** 0 days and **(b)** 7 days. Figure 2 shows the phase identification results using XRD. An obvious peak appearing around 30\({}^{\circ}\) for BG_Ti100 at 0 days can be due to the calcium and phosphate compound formed after calcination at 500 \({}^{\circ}\)C. After soaking in SBF for 7 days, all samples appeared to peak in terms of apatite levels (HA). This was most obvious for the BG sample. The samples in decreasing order of apatite levels are as follows: BG_Ti75, BG_Ti50, BG_Ti25, BG_Ti100, and SiO2. This demonstrated that all samples had the ability to deposit HA. Figure 3 shows the pH value of SBF after the immersion of bioceramics composed of silica and titanium oxide with various concentrations of titanium oxide for 7 days.