Solid-state formation of lithium ferrites from mechanically activated Li2CO3-Fe2O3 mixtures

The formation of lithium ferrites (LiFe5O8 and LiFeO2) from mechanically activated mixtures of Li2CO3-Fe2O3 has been studied using thermal analysis (TGA, DSC), evolved gas analysis (TG/FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and particle size analysis. It is shown that mechanical activation of the precursors considerably enhances the reactivity of the solid system analysed and makes it possible to obtain reaction products with a much lower expense of thermal energy. In particular, lithium ferrites can be obtained at temperatures at least 160 degreesC lower than those necessary in the absence of mechanical activation. Moreover, both the microstructure and the allotropic ratio of the products, as well as the reaction path, are affected by mechanical activation. (C) 2002 Elsevier Science Ltd. All rights reserved.