Therefore, the characteristic, reversible tetragonal -cubic phase transition in LLZO is believed to be 620 -650°C , while the smaller cell volume La3Sn2Li7O12 (LLSnO) exhibits a phase transition ~750 -800°C . This suggests that the cell volume is potentially key to dictating the phase transition. Dong et al. investigated tetragonal garnets of the formula La3Zr2-xLi7CexO12 (0 ≤ x ≥ 0.75) via XRD studies. This showed a reduction in tetragonality for these Li7 garnets on Ce doping, attributed to the larger ionic radius of Ce 4+ . This decreased the tetragonal-cubic transition temperature to 325°C compared to LLZO suggesting further that increased cell volume corresponds to lower transition temperatures .