Magnetic properties of Li1-xNi1+xO2(0 less than or similar to x less than or similar to 0.08)

Magnetic properties of L(1-x)Ni(1+x)O(2) (0 less than or similar to x less than or similar to 0.08) crystallizing in the alpha-NaFeO2 structure were studied by SQUID magnetometry. A sample with x less than or similar to 0.01 prepared from Li2O2 and Ni0.77O at 650 degrees C follows the Curie-Weiss law from 350 to 80 K with mu(eff) (effective Bohr magneton) of 1.91 mu(B) and Theta (Weiss temperature) of +29.5 K. A spin glass-like thermomagnetic hysteresis with a cusp at 8 K was observed. Samples with larger x values exhibit ferromagnetic moments, typically 0.3 mu(B)/Ni (x similar to 0.08) at 5 K. From these and other results we conclude that the dominant intra-Ni layer interaction is ferromagnetic and that excess Ni ions located in the Li layers introduce strong ferromagnetic inter-Ni layer interactions. Possible importance of orbital-spin coupling and frustration in orbital ordering will be raised to the magnetism of ideal LiNO2, in which Ni3+ (S=1/2) ions with twofold orbital degeneracy form a ferromagnetic triangular lattice. (C) 1996 Academic Press, Inc.