Phase transitions in LiCoO 2 thin films prepared by pulsed laser deposition

Rong Huang, Taro Hitosugi, Craig A.J. Fisher, Yumi H. Ikuhara, Hiroki Moriwake, Hideki Oki, Yuichi Ikuhara

    Research output: Contribution to journalArticlepeer-review

    24 Citations (Scopus)


    Microstructures of epitaxial LiCoO 2 thin films formed on the (0 0 0 1) surface of sapphire (α-Al 2O 3) substrates by pulsed laser deposition at room temperature and annealed at 600°C in air were investigated by a combination of selected-area electron diffraction, high-resolution transmission electron microscopy, spherical-aberration-corrected high-angle annular dark-field scanning transmission electron microscopy, and electron energy-loss spectroscopy. As-deposited LiCoO 2 thin films consisted of epitaxial grains of the fully cation-disordered phase (γ) with a cubic rock-salt structure. During annealing, this cubic-structured phase transformed into the fully ordered trigonal (α) phase oriented with its basal plane parallel to the surface of the sapphire substrate. Although overall the film appeared to be a single crystal, a small number of Co 3O 4 grains were also observed in annealed thin films, indicating that some Li and O had been lost during processing. The atomically sharp interface between the film and substrate also became rougher during annealing, with step defects being formed, suggesting that a localized reaction occurred at the interface.

    Original languageEnglish
    Pages (from-to)1101-1107
    Number of pages7
    JournalMaterials Chemistry and Physics
    Issue number2-3
    Publication statusPublished - 2012 Apr 16


    • LiCoO
    • Microstructure
    • PLD
    • STEM
    • Thin films

    ASJC Scopus subject areas

    • Materials Science(all)
    • Condensed Matter Physics


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