Effect of the Reaction Medium on the Mechanochemical Synthesis of LiAlO2

An unactivated mixture of aluminum hydroxide (gibbsite) and lithium carbonate and a mixture mechanically activated in an AGO-2 planetary mill were heat-treated in air and under vacuum (0.05 Pa) at temperatures of up to 800–850°C, and the phase composition of the heat treatment products was determined by in situ X-ray diffraction. The results demonstrate that, in the case of the unactivated mixture or after mechanical activation for 1 min, heat treatments in air and under vacuum lead to the formation of α-LiAlO2 and γ-LiAlO2, respectively. After mechanical activation for 5 or 10 min, heat treatment both in air and under vacuum leads to γ-LiAlO2 formation. A possible mechanism behind the effect of the reaction medium on the phase composition of LiAlO2 is analyzed.