Influence of the cation distribution on the physical properties of the diluted magnetics Li1.33Ti1.67O4/Co2TiO4

Abstract

Spinel samples of Li1.33xCo2-2xTi1+0.67xO4 crystallize in two space groups: Fd 3 m for 0less than or equal tox:less than or equal to0.40 and x=1, and P4(3)32 for 0.50less than or equal toxless than or equal to0.875. In S.G. P4(3)32 magnetic Co2+ ions occupy 8c sites (for x=0.75 and 0.875), or 8c, 4b and 12d sites (for x=0.50). In x=0.25 and 0.40 samples Co2+ occupy both 8a and 16d cation sites of the S.G. Fd 3 m [1]. Observed differences in magnetic 2+ behaviour of the samples are induced by crystallographic distribution of Co2+. Possible paths for exchange interactions in S.G. P(4)332 were analysed. It was found that the superexchange is the dominant exchange mechanism where Co2+(8c)-O(24e)-CO2+(12d) path was the most important one. On the basis of the results on crystallographic distribution we suggest x=0.50 sample as potential electrode material in Li ion rechargeable batteries.