SUPERSTRUCTURE ANALYSES ON SINGLE-CRYSTALS OF LI0.8VO2

Flux-grown single crystals of ordered rock-salt-type Li1-xVO2 (x approximate to 0.2), which form a significant superstructure in the ab-plane and along the c-axis at room temperature, have been analyzed by EXAFS and X-ray diffraction methods. The results show that two-dimensionally oriented V ions in the ab-plane form a cluster of triangular V-3 trimers with a displacement of 0.160 Angstrom from the unclustered position and that the superstructure along the c-axis is due to a stacking order of the V-3 trimers along the c-axis. The intensities of the superstructure patterns in X-ray precession photographs are analyzed in terms of the periodic intensity distribution (PID) function, and the most common diffraction streak is caused by a racemate-like stacking sequence of the clustered V layers. (C) 1995 Academic Press, Inc.