Mechanochemical synthesis of γ-LiAlO2 studied by 6Li and 27Al NMR and synchrotron X-Ray diffraction

Abstract

The structural transformations accompanying the mechanochemical synthesis of fine-particle γ-LiAlO2 have been studied by 6Li and 27Al NMR and in situ X-ray diffraction. Mechanical activation of a mixture of aluminum hydroxide and lithium carbonate in an AGO-2 planetary mill results not only in size reduction, intermixing, and partial amorphization of the starting materials but also in the mechanochemical synthesis of a carbonate form of aluminum lithium hydroxide. Subsequent heat treatment of the mechanically activated mixture leads to the release of water and carbon dioxide molecules and the formation of an X-ray amorphous phase containing aluminum in octahedral and tetrahedral oxygen coordination. The X-ray amorphous material converts to gamma lithium aluminate through an intermediate phase.