Phase transitions and structural mechanisms of the formation of LiCoO2 polymorphic modifications

The structural mechanisms of formation of the low-symmetry phases of the LiCoO₂ compound from the praphase with a sodium chloride structure are investigated in the framework of the Landau phenomenological theory of phase transitions. The possibility of forming new modifications of the LiCoO₂ compound is predicted. The calculated structures of some possible low-symmetry phases of lithium cobaltite are described, and the possible phase diagrams are calculated. It is demonstrated that the most stable modifications of the LiCoO₂ compound (the spinel-like and rhombohedral modifications) can transform into each other through a first-order phase transition.