XRPD and TG analyses showed that milling a 1:5 (molar ratio) mixture of Li2CO3-Ga2O3 results in the partial formation of LiGa5O8 at room temperature. Furthermore complete LiGa5O8 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 LiGa5O8 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 Li2CO3-Ga2O3 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 (LiGaO2) and on its crystal size is less evident than in the case of the 1:5 composition. (C) 2004 Elsevier B.V. All rights reserved.