Reinvestigations of the Li₂O–Al₂O₃ system. Part I: LiAlO₂ and Li₃AlO₃

Reinvestigations of the Li₂O–Al₂O₃ system focused on the synthesis and properties of LiAlO₂ and Li₃AlO₃ phases have been performed with the help of XRD and IR measuring techniques and Li₂CO₃, LiOH·H₂O, Al₂O₃-sl., α-Al₂O₃, Al(NO₃)₃·9H₂O and boehmite as reactants. Results of investigations have shown the formation of α-, β-, and γ- polymorphs of LiAlO₂. It was found that only the use of LiOH·H₂O as a reactant yields to β-LiAlO₂ as a reaction product. On the other hand, it was proved that Li₃AlO₃ does not form in the Li₂O–Al₂O₃ system. A new method for the synthesis of α-LiAlO₂ was developed, consisting in grinding the mixture of Li₂CO₃ and Al(NO₃)₃·9H₂O and heating the obtained paste at the temperature range of 400–600 °C. The IR spectroscopy was used to characterize obtained phases.