Effect of sintering temperature on structure and ionic conductivity of Li7 − xLa3Zr2O12 − 0.5x (x = 0.5 ~ 0.7) ceramics

Li7 − xLa3Zr2O12 − 0.5x (LLZ) ceramics with garnet-type structure were prepared via the conventional solid-state reaction method. The results showed that the sintering temperature has a significant effect on the crystal structure and phase composition, and thus ionic conductivity, of the LLZ ceramics. The ionic conductivity at room temperature of the ceramic samples increased with the crystal structural transition from tetragonal to cubic structure, as the sintering temperature increased; and reached a value of about 3.6 × 10− 4 S/cm for the cubic LLZ sample sintered at 1230 °C, but LLZ would be decomposed at 1250 °C.

► Li7La3Zr2O12 (LLZ) ceramics were prepared via sintering at different temperatures.
► The sintering temperature significantly affects the structure and ionic conductivity.
► As sintered below 1150 °C, LLZ is of tetragonal structure with low conductivity.
► The ionic conductivity of cubic LLZ is about 10–4 S/cm as sintered around 1200 °C.
► But LLZ decomposes into La2Zr2O7 at 1250 °C.