Sur de nouveaux bronzes oxygénés de formule NaχCoO2 (χ1). Le système cobalt-oxygène-sodium

An investigation of the sodium-cobalt-oxygen system allows the isolation of four new bronze type phases with the formula Naχ.CoO2 (χ 1). The structure consists of sheets of octahedra (CoO2)n between which are inserted the sodium ions. Their structures differ from one another by the stacking sequence of the oxygen layers, and by the distortions introduced as a result of the ordering of vacancies among the sodium layers. For phases containing high sodium content, the coordination of the sodium is octahedral; for phases containing smaller amounts of sodium, the coordination becomes trigonal-prismatic.