To conclude, it is suggested that the primary factor in the determination the temperature of the tetragonal -cubic phase transition in the Li7-garnet systems is the B site, which is suspected to arise from the fact that this cation helps to dictate the garnet framework structure, in contrast to the A site, which occupies the cavities within the framework of corner linked octahedra and tetrahedra. This is illustrated by the fact that octahedral site doping showed significant changes to the transition temperature, whereas negligible changes were observed for A site doping. Changes can be correlated to the degree of tetragonality which appears to be dependent on B site dopant size, rather than the cell volume. This work shows that as the degree of tetragonality of the garnet increases, the transition temperature increases too. Therefore, it is hypothesized that the octahedral site is instrumental in determining the tetragonality of the phase, and hence doping at this site with larger cations is the best method in lowering the transition temperature. A similar affect could also be the case for doping in the XO4 tetrahedra (which are also part of the garnet framework) and may help to explain the stability of Li site doping by Ga/Al and subsequent formation of the cubic phase.