Crystal data and structural relation between Pb₆GeO₈.Pb₁₁Ge₃O₁₇ and PbO

Transparent yellow-greenish single crystals of Pb₆GeO₈ were obtained by spontaneous crystallization from a melt with a molar ratio of PbO:GeO₂ = 4.7:1. The compound is monoclinic, probable space group P2₁/a, a = 52.665 (12), b = 15.063 (4), c = 23.949 (6) Å and β = 111.03 (5)°; D_m(293 K) = 8.65 (3), D_x = 8.653 Mg m⁻³ for Z = 64 formula units. Pb₁₁Ge₃O₁₇ was synthesized by sintering high-purity oxides PbO and GeO₂ of molar ratio 3.69:1 at 990 K. The compound is also monoclinic, probable space groups C2/c or Cc, a = 25.117 (5), b = 15.440 (2), c = 45.529 (13) Å and β = 103.20 (4)°; D_m(293 K) = 8.55 (2), D_x = 8.560 Mg m⁻³ for Z = 32.