Mechanochemically assisted solid-state synthesis of lithium gallates (LiGa 5O 8 and LiGaO 2)

Abstract

XRPD and TG analyses showed that milling a 1:5 (molar ratio) mixture of Li 2CO 3–Ga 2O 3 results in the partial formation of LiGa 5O 8 at room temperature. Furthermore complete LiGa 5O 8 formation is obtained at a sensibly lower temperature than it is the case with a physical (unmilled) mixture. The X-ray profile analysis, performed both by the Debye–Scherrer equation and by the Warren–Averbach method, shows that the crystal size of LiGa 5O 8 prepared from the milled mixture is significantly lower (6–9 nm) than that of the sample obtained (54 nm), at higher temperatures, from the physical mixture. In the case of the 1:1 (molar ratio) mixture of Li 2CO 3–Ga 2O 3 no evidence is obtained of formation of any of the lithium gallates at room temperature. Furthermore, the influence of mechanical activation on the temperature of formation of the reaction product (LiGaO 2) and on its crystal size is less evident than in the case of the 1:5 composition.