Crystal Structure of Sr0.35CoO2 Compound Studied by High-Resolution Electron Microscopy

The modulated crystal structure of Sr 0.35 CoO 2 is studied by electron diffraction measurement and high-resolution electron microscopy. Sr 0.35 CoO 2 consists of two interpenetrating subsystems of CoO 2 sheets and intercalated Sr layers. Both subsystems have common a - and c -axes with a =4.80 Å and c =11.33 Å. The two subsystems of Sr 0.35 CoO 2 are mutually commensurated parallel to the b -axis, i.e., b 1 =2.80 Å for the CoO 2 sheets and b 2 =8.41 Å for the intercalated Sr layers, showing that the axial b 1 / b 2 ratio is 1/3, i.e., rational. The high-resolution images taken with the incident electron beams parallel to the a -, b -, and c -axes clearly exhibit characteristic atomic arrangements.