Phase transitions in LiCoO2 thin films prepared by pulsed laser deposition

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

来源：Materials Chemistry and Physics, 2012, 133(2-3): 1101-1107.

DOI：10.1016/j.matchemphys.2012.02.022

• LiCoO2
• Thin films
• PLD
• Microstructure
• STEM

Microstructures of epitaxial LiCoO2 thin films formed on the (0 0 0 1) surface of sapphire (alpha-Al2O3) substrates by pulsed laser deposition at room temperature and annealed at 600 degrees 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 LiCoO2 thin films consisted of epitaxial grains of the fully cation-disordered phase (gamma) with a cubic rock-salt structure. During annealing, this cubic-structured phase transformed into the fully ordered trigonal (alpha) 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 Co3O4 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.

• 出版日期2012-4-16
• 单位华东师范大学