@article{oai:ynu.repo.nii.ac.jp:00003925,
 author = {Nagasawa, K. and Nakatsugawa, Hiroshi},
 journal = {Proceedings of the Symposia of the 8th IUMRS International Conference on Advanced Materials (IUMRS-ICAM) October 8-13},
 month = {},
 note = {application/pdf, The electron density distributions of ＄γ-Na_{x}CoO_{2}＄ have been obtained by the maximum entropy method and the Rietveld analysis using powder x-ray diffraction data at room temperature.In the Rietveld refinement, the deviation of (008) and (108) peaks is very large relative to that of other reflections, and the change in x-ray diffraction data at 10K and room temperature. This indicates that electron density distributions in ＄γ-Na_{x}CoO_{2}＄ are slightly modulated with increasing x. In fact, there found to be the obvious overlapping of the charge density between O-O network and Co ions, but no significant overlapping with increasing x. This is the direct observation of decrease of covalency between O 2p and ＄Co t_{2g}＄ in the ＄CoO_{2}＄ layer with increasing the sodium content.},
 pages = {2809--2812},
 title = {Crystal structure, electric and magnetic properties in Nax＄CoO_{2}＄},
 volume = {29},
 year = {2004}
}