High-resolution transmission electron microscopy study of Ca₃Co₄O₉

Abstract

The crystal structure of Ca₃Co₄O₉ was investigated using high-resolution transmission electron microscopy (HRTEM) and the image-simulation method. The c^* was 10.8Å and the b parameters were 4.56Å for the Ca₂CoO₃ block and 2.82Å for the CoO₂ sheet. The [110] zone axis HRTEM images confirmed that Ca₃Co₄O₉ has a modulated layered structure with modulation. For the first time, the atomic positions of the Ca and Co atoms in the Ca₂CoO₃ block were identified, corresponding to three rows of dark spots in the [110] direction. The observed HRTEM images for Ca₂CoO₃ agreed well with the calculated images based on the structural model obtained by the Rietveld refinement method.

Ca₃Co₄O₉, HRTEM, image simulation