This approximately constant average grain size may occur due to two reasons: (1) some small Li2Mg3TiO6 grains were formed by the impurities during the sintering process and (2) low temperature sintering could not provide the necessary energy to promote grain boundary migration. However, the average grain size increased to ~100 nm at 800°C, followed by a dramatic increase from ~390 to 1200 nm at a temperature range 850°C –950°C.