Phase transitions in LiCoO2 thin films prepared by pulsed laser deposition

► Epitaxial LiCoO2 thin films were formed on the Al2O3 (0 0 0 1) substrate by PLD at room temperature and annealed at 600 °C in air. ► The orientation relationship between film and substrate is revealed. ► Crystalline phases in the RT deposited and annealed thin films are clearly identified. ► Atomic level interface structure indicates an interface reaction during annealing. ► A phase transition mechanism from fully disordered LiCoO2 to fully ordered LiCoO2 is proposed.