DEFECT STRUCTURE OF LI-1-XCO0.5XVO3 (0-LESS-THAN-X-LESS-THAN-OR-EQUAL-TO-0.35) SOLID-SOLUTIONS

Phase relations in the Li2O-CoO-V2O5 system were studied in detail by x-ray diffraction, IR spectroscopy, and electron spin resonance. The s toichiometry range of the Li1-xCo0.5xVO3 solid solution is found to be 0 < x less than or equal to 0.35. At x = 0.35, the solid solution is involved in equilibria with Li2.4V6O16, Co(VO3)(2), Co2V2O7, and LiCoV O4. IR absorption data suggest that some of the vanadium-oxygen polyhe dra in the structure of Li1-xCo0.5xVO3 are distorted and brought close r together, producing nearest neighbor configurations similar to those in vanadium bronze. In cobalt-rich solid solutions, extrinsic defects prevail. The boundary of intrinsic disordering is found to lie at x = 0.04 from electrical conductivity measurements and 0.06 from ESR data . Analysis of defect chemistry and conductivity data indicates that th e majority current carriers in the solid solution are electrons.