STRUCTURAL STUDIES OF LI0.7VO2 IN THE TEMPERATURE-RANGE 20-300-DEGREES-C

The ordered rock-salt type compound Li//0//. //7VO//2 has recently been found to exhibit some unusually large hysteresis effects in its magnetic and thermal properties between 150 and 280 degree C, related to the magnetic transition known to occur at about 190 degree C in LiVO//2. X-ray and neutron powder diffraction measurements have been made on samples of Li//0//. //7VO//2 in an effort to classify structural changes believed to accompany this transition but not hitherto reported in any detail. Rietveld refinement was carried out on X-ray data collected at these temperatures and on neutron data collected at 35 degree C, the main change being an increase in the V-O and V-V distances from 1. 98 and 2. 84 A at 24 degree C to 2. 02 and 2. 91 A at 263 degree C, respectively.