LiVO_2の結晶化学 Crystal Chemistry of LiVO_2
Large single crystal plates of Li<SUB>1-<I>x</I></SUB>VO<SUB>2</SUB> (<I>x</I>≈0.2) have been first grown using the Li<SUB>2</SUB>O-B<SUB>2</SUB>O<SUB>3</SUB> flux method. Precession photographs reveal that an additional superstructure is formed on the basic ordered rock salt (ORS) structure at room temperature, and is released above transition temperature forming the ideal ORS structure. Small amount of LiV<SUB>2</SUB>O<SUB>4</SUB> decomposed partially from the Li<SUB>1-<I>x</I></SUB>VO<SUB>2</SUB> crystals on heating above <I>Tc</I>is also confirmed.<BR>Average structure analysis based on the ORS structure reveals that there exists large anisotropy on the thermal ellipsoid of V-site. The results of X-ray diffraction and the EXAFS analysis at room temperature indicate that the superstructure is originated in formation of the V<SUB>3</SUB>-trimers, and the displacement of V ions is estimated to be 0.16Å. Three kinds of stacking sequence of V<SUB>3</SUB>-trimers are proposed to explain the intensity distributions of superstructure reflections.<BR>Temperature dependence of electrical resistivity and magnetic susceptibility are measured. Significant anisotropy in both of them is observed, indicating two-dimensional feature of this compound.
日本結晶学会誌 38(4), 280-287, 1996-08-30
The Crystallographic Society of Japan