We yielded the intermediate by pre-sintering a mixture of CH₃COOLi∙2H₂O and anatase TiO₂ at 500˚C, and showed XRD patterns as (a); a green line in Figure 1(A) and Figure 1(B) by applying the 30 m²/g and 50 m²/g anatase TiO₂ respectively. The intermediate was identified with unreacted TiO₂ and Li₂TiO₃ known as a sub- phase of Li₄Ti₅O₁₂. Li₂TiO₃ has been understood by a phase diagram of Li₂O-TiO₂ among TiO₂, Li₂TiO₃ and Li₄Ti₅O₁₂, which shows an accurate mixed rate at Li and Ti atoms [20] . A Ti site of Li₂TiO₃ and Li₄Ti₅O₁₂ is common in center of an octahedron, while a Li site exists in a tetrahedron in the case of Li₂TiO₃. Li₂TiO₃ show inactivity as the electrode not to charge and discharge Li ions [21] .

To obtain Li₄Ti₅O₁₂, the intermediate was sintered at 700˚C, and the identification was shown as (b); a red line in the XRD patterns, which obtained main Li₄Ti₅O₁₂ peaks and slight peaks of Li₂TiO₃, and was not able to confirm the unreacted TiO₂. This result is not enough to obtain a single phase Li₄Ti₅O₁₂ at the sintering temperature although all unreacted TiO₂ is consumed. Then, effect of the specific surface area by applying the 30 m²/g or 50 m²/g anatase TiO₂ was not confirmed in Figure 1(A) and Figure 1(B). In the sintering temperature at 750˚C, the single phase Li₄Ti₅O₁₂ was obtained by applying either specific surface area of the anatase TiO₂ as shown in (c); a blue line in the patterns. On the other hand, the peak intensity was strong by applying the anatase TiO₂ of 50 m²/g than that of 30 m²/g, which would be superior to the crystallization.

Now, to estimate the synthesized rate of the single phase Li₄Ti₅O₁₂, we defined a single phase rate in a following equation.

Single phase rate (%) = [S(Li₄Ti₅O₁₂)/{S(Li₂TiO₃) + S(Li₄Ti₅O₁₂)}] × 100

Here, “S” shows area of the peaks. The value was nearly same in 86% in Figure 1(A) and 89% in Figure 1(B) at 700˚C, and was 100% at 750˚C in any cases. Consequently, the effect of the specific surface area in the anatase TiO₂ does not be indicated by the single phase rate, while the sintering temperature gave the great effect.

The intermediate was produced by the pre-sintering the mixture of CH₃COOLi・2H₂O and anatase TiO₂ at 500˚C, and was showed in Figure 2(A); 30 m²/g and Figure 2(B); 50 m²/g anatase TiO₂. These results showed two

grain species to differ from contrast, which will indicate the unreacted TiO₂ and Li₂TiO₃ as shown in the XRD pattern. The intermediate would consist of the heterogeneous parts by them. The average grain size of the intermediate was different from 60 nm at Figure 2(A) and 30 nm at Figure 2(B), and the specific surface area was about 26.6 m²/g and 33.0 m²/g respectively. The specific surface area of the applying anatase TiO₂ will give the effect to the average grain size and specific surface area of the intermediate.

Figure 3 showed homogeneous grains without almost the contrast by the sintering at 700˚C or 750˚C, especially the heterogeneous parts was not observed at 750˚C at all. In fact, the single phases rate is 100%, which would support acquisition of the single phase Li₄Ti₅O₁₂. While the average grain size trended for greater with the high temperature about Figure 3(A); 101 nm, Figure 3(B); 83 nm, Figure 3(C); 124 nm and Figure 3(D): 87 nm, it will show no much change by applying the 50 m²/g anatase TiO₂. Similarly, the specific surface area was about (a); 8.3 m²/g, (b); 14 m²/g, (c); 5.1 m²/g and (d): 12 m²/g, hence the single phase Li₄Ti₅O₁₂ was obtained with high specific surface area by the 50 m²/g anatase TiO₂ at sintering temperature of 750˚C. Furthermore, the crystallization will be higher by the grain of a horned shape.

Figure 4 shows TEM images at pre-sintering temperature of 500˚C. The minute TiO₂ particles will encircle the Li₂TiO₃ at the 50 m²/g anatase TiO₂ specially, which may take advantage of the Li₄Ti₅O₁₂ synthesis by the following sintering. These images did not indicate a clear morphology like a facet in this pre-sintering, and would show a very low crystallization.

TEM images show the samples by the sintering temperature of 700˚C or 750˚C in Figure 5. The Li₄Ti₅O₁₂ particles would be the higher crystallization to form at an angular grain which included the facets in the morphology, while the sintering temperature and the specific surface area of the anatase TiO₂ would hardly give the effect for the synthesized Li₄Ti₅O₁₂ not to be obtained about the clear differences. The morphology have been reported about the synthesis by using nano-particle or nano-wire TiO₂, which have described that the nano-particle or nano-wire Li₄Ti₅O₁₂ was obtained on keeping the TiO₂ morphology like a mold [22] [23] . This knowledge will suggest the synthesis mechanism for the solid phase synthesis of Li₄Ti₅O₁₂, which the (002) face of Li₂TiO₃

plays a role of the mold in the spinel structure. These may show that the mobility of titanium ions is improved to close to the (002) Li₂TiO₃ and the (111) Li₄Ti₅O₁₂.