ON THE CRYSTAL-STRUCTURE OF BI2TE4O11

Bi2Te4O11 is monoclinic, space group P2(1)/n; the lattice parameters derived from a Guinier powder pattern (Si standard) are: a = 6.9909(3), b = 7.9593(3), c = 18.8963(8) angstrom, beta = 95.176(3)-degrees, Z = 4, V = 1047.15 angstrom3. The structure was solved independently from both single-crystal X-ray data and a combination of X-ray and neutron powder data. It is an anion-deficient superstructure of fluorite in which can be recognized the ordered intergrowth of fluorite-type Bi2Te2O7 and rutile-type Te2O4. Lone-pair electrons are stereochemically active.