Crystal structure, electric and magnetic properties in Nax＄CoO_{2}＄

概要

論文の詳細を見る
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.