Moreover, almost all the reaction products turned to cubic-shaped crystals when the temperature reached 220 °C (Fig. 1i). This result suggests that the shape of as-prepared LTP crystals can be modified by adjusting the hydrothermal temperature. Moreover, the development of the LTP film strongly depends on the duration of the hy- drothermal reaction. At the 6th hour, as observed in Fig. 1a, d and g, the LTP film only partially covered the substrate. Thereafter, the whisker cluster (Fig. 1b and e), as well as the cubic particle (Fig. 1h), gradually became larger and covered almost all of the substrate. After 48 h,