Preparation and Structural Investigation of Bi16(Sr,Ca)14O38

Single-crystal X-ray diffraction was used to investigate the structure of the ternary oxide of approximate formula Bi 14 (Sr,Ca) 12 O 33 . The crystal examined was found to have a composition Bi 2 Sr 0.68 Ca 1.07 O 4.75 or Bi 16 Sr 5.44 Ca 8.56 O 38 as a result of refinement. It crystallizes in the monoclinic space group (C2/m), with cell parameters a = 21.764 (4) A, b = 4.3850 (13) A, c = 12.905 (3) A, β = 102.72 (2)°, and V 1201.2 (5) A 3 . Strontium and calcium ions were found to substitute for each other. The structure consists of a network of alkaline-earth oxide polyhedra with broad channels parallel to the b axis, in which the bismuth ions reside. Two out of four crystallographically distinct Bi ions form infinite Bi-O zigzag ribbons of edge-linked Bi-O units, while each of the other two form oxygen corner-shared Bi-O chains along b. The lone pair electrons of the Bi ions point toward each other in the channels.