Mechanically stimulated thermal synthesis of lithium aluminates

Abstract

The influence of the conditions of preliminary mechanical activation of a mixture of gibbsite and lithium carbonate in a planetary-type activator and the conditions of subsequent heat treatment on the phase composition of lithium aluminates is studied. It is shown that for the formation of γ-LiAlO2 it is necessary that at the stage of mechanical activation of the mixture an almost complete amorphization of aluminum hydroxide occurs, and the air heat treatment is carried out at a temperature above 750 °C. Thermal treatment of a mechanically activated mixture in the atmosphere with the partial water vapor pressure of below 1 Pa allows the synthesis of γ-LiAlO2 without significant amorphization of aluminum hydroxide at above 600 °C. For the synthesis of α-LiAlO2 preliminary mechanical activation should not lead to the amorphization of aluminum hydroxide, and the process of heat treatment in the air should be carried out at temperatures below 700 °C. The mechanism of formation of highly dispersed lithium aluminates during mechanical activation and subsequent heat treatment of a mixture of gibbsite and lithium carbonate is discussed.