Über Hexagonale Perowskite mit Kationenfehlstellen. XI. Die Stapelvariante Ba6W4□2O18

On Hexagonal Perovskites with Cationic Vacancies. XI. Stacking Polytype Ba₆W₄□₂O₁₈ The white Ba₆W₄□₂O₁₈, with a cation/vacancy ratio of 2:1 for the octahedral holes, is the first representative of a new stacking polytype for this formula type. It crystallizes in a rhombohedral six layer-structure with a_hex = 10.13₀ Å c_hex = 13.96₀ Å Z = 3 (ρ_exp = 7.3₈ g/cm³; ρ_calc = 7.41₈ g/cm³).