A NOTE ON THE LI-CU-O SYSTEM

In the Li-Cu-O system two new ternary phases have been found, tentatively described by the stoichiometries LiCu3O3 and LiCu2O2, and both containing Cu(I) and Cu(II). They exhibit p-type "hopping" conduction owing to localized charge carriers. Their powder patterns are successfully indexed on high-symmetry cells where the dimensions depend on a slightly variable stoichiometry. LiCu3O3 is tetragonal with a = 2.815 (.square root 2) angstrom and c = 8.88 angstrom. LiCu2O2 is orthorhombic with a = 5.72 angstrom, b = 2.86 angstrom and c = 12.4 angstrom. Li3Cu2O4, containing Cu(II) and Cu(III), is indexed on a C-centred monoclinic cell: a = 9.958 angstrom, b = 2.777, c = 7.281 angstrom and beta = 118.77-degrees. The solubility of lithium in CuO is maximally Li0.06Cu0.94O for supersaturation at 1100 K. The equilibrium solubility limit is about Li0.02Cu0.98O, for which the solid solution is still semiconducting. The temperature dependence of the magnetic susceptibility is similar to that of pure CuO but T(N) is considerably lower.