Ca-ion superstructures such as 3a×3a (hexagonal) and 2a×3a (orthorhombic) in layered Ca0.33 CoO2 crystalline film, which were prepared by the reactive solid-phase epitaxy and the subsequent ion-exchange treatment, were directly distinguished by using spherical-aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The fluctuation of Ca intensities in the HAADF-STEM image indicates the existence of many Ca vacancies in the 2a×3a orthorhombic superstructure, which is consistent with the partial occupation of Ca (x=0.33) in the cation sites of x=0.5.
|Journal||Applied Physics Letters|
|Publication status||Published - 2008|
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)