A NEUTRON POWDER DIFFRACTION STUDY OF THE ORDERING IN LIXNI1-XO

Lithium nickel oxide phases, LixNi1-xO (x=0.400, 0.347, 0.320) have been synthesized by direct solid state reaction of Li2CO3 and NiO. The structures and cation distribution have been determined at ambient temperature and 60 K from time of flight neutron powder diffraction data collected on the Neutron Powder Diffractometer at LANSCE, Los Alamos National Laboratory. The rhombohedral distortion and the order parameter characterizing the lithium distribution have been determined as x decreases. The partitioning of Ni2+ and Ni3+ between the two layers has been inferred from the average metal-oxygen bond lengths for the two inequivalent sites.