Low-temperature synthesis of Li7La3Zr2O12 with cubic garnet-type structure

Highlights: ► One-step synthesis and its optimization of cubic garnet Li7La3Zr2O12 at 750 °C. ► Instability above 800 °C of the Al-free cubic Li7La3Zr2O12. ► Li+-ion conductivity without adventitious Al3+. -- Abstract: In this paper, we report the direct synthesis of Li7La3Zr2O12 with the cubic garnet-type structure at low temperature with a lattice constant of 13.0035 Å. The synthesis condition is optimized to be at 750 °C for 8 h with 30 wt% excess lithium salt. No intermediate grinding was involved in this straightforward route. Without the adventitious of Al3+, the cubic Li7La3Zr2O12 is unstable above 800 °C and has an ionic conductivity of the order of 10−6 S cm−1.