2011 年 53 巻 6 号 p. 409-415
Neutron powder diffraction patterns of 2H- and 3R-NaxCoO2·yD2O (x~0.35, y~1.3), which show superconductivity with Tc of about 4.7 K, show conspicuous diffuse maxima presumed to originate from the Na/D2O part in addition to sharp reflections due to the CoO2 part. The structure is treated as an interpenetration of two layered structures, the CoO2 part (a1=b1=2.82 Å) and the Na/D2O part (a2=b2=3.26 Å). A model of the short-range-order stacking of the Na/D2O part is expressed and diffuse scattering intensities simulated using the matrix method satisfactorily explain the neutron diffraction patterns. Information about atomic coordinates was obtained based on superstructure expression with A=B=2a1=a2√3=5.64 Å including short-range order stacking.