High-pressure synthesis of solid solutions between trigonal LiNiO2 and monoclinic Li[Li1/3Ni2/3]O-2

摘要

High-pressure synthesis in an oxygen-rich atmosphere yields solid solutions between LiNiO2 and Li2NiO3 over the whole concentration range. Structural characterization of the high-pressure oxides was performed using powder XRD, SEM analysis, IR spectroscopy, EPR spectroscopy at 9.23 and 115GHz and magnetic susceptibility measurements. The crystal structure of Li[LixNi1-x]O-2, 0 ≤ x ≤ 1/3, changes from trigonal R-3m to monoclinic C2/m at Li-to-Ni ratio of 2 (orx = 1/3). The incorporation of Li into NiO2-layers causes a decrease in the mean Li-O and Ni1-xLix-O bond distance. Li and Ni ions in the mixed Ni1-xLixO2-layers display a tendency to order at a short length scale in such a way that mimics the Li1/3N2/3-arrangment of the end Li[Li1/3M2/3]O-2 composition. The charge distribution in these oxides proceeds via Ni3+ and Ni4+ ions. © 2005 Elsevier Inc. All rights reserved.