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.