Fig compares the morphologies and microstructures of the samples

High temperature sintering usually lead to the overgrowth of crystalline particles, the formation of impure phase associated with the volatilization of part of components during molten salt synthesis. Fig. 4 reveals the XRD patterns of the samples obtained at various temperatures for 8 h. By reducing the calcination temperature to 700 °C, single phase sodium lithium titanium oxide was obtained when the amount of lithium carbonate was 105% of the theoretical amount. From the X-ray diffraction curve of the sample synthesized at 700 °C, it I-BET151 is evident that the diffraction peak positions and the relative intensities of the prepared sample are assigned to Na2Li2Ti6O14 standard powder diffraction file (PDF 52-0690). It demonstrates that the calcination temperature played an important role in the procedure of synthesizing Na2Li2Ti6O14, and the amount of the elimination of lithium at higher temperatures led to the formation of impure phase. Fig. 5 displays SEM images of the materials prepared at various temperatures for 8 h. As presented in Fig. 5(c), the sample obtained at 900 °C is mainly composed of the whiskers and the particles. However, the sample synthesized at 800 °C is mainly composed of the particles due to the decreasing of the evaporation of lithium. Additionally, with the decreasing of the calcination temperature, the crystal size decreases. As shown in Fig. 5(a), no visible aggregation is observed for as-synthesized samples, which can be attributed to the existence of molten salt medium during the reaction process.