Synthesis, Structures, Magnetic Properties, and Absorption Spectra of the Alkaline Oxocobaltates(II): Li₆CoO₄, Na₄CoO₃, and Na₁₀Co₄O₉

The synthesis of Li6CoO4, Na4CoO3, and Na10Co4O9 and the refinements of the crystal structures of the two sodium compounds are reported. The physical properties of these materials have been studied by measuring the absorption spectra and the susceptibility. An interpretation of these data is presented for the tetrahedral [CoO4]6- and trigonal planar [CoO3]4- complexes in terms of the angular-overlap model.