PREPARATION AND STRUCTURAL INVESTIGATION OF BI-16(SR,CA)(14)O-38

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 Bi2Sr0.68Ca1.07O4.75 or Bi16Sr5.44Ca8.56O38 as a result of refinement. It crystallizes in the monoclinic space group (C2/m), with fell parameters a = 21.764 (4) Angstrom, b = 4.3850 (13) Angstrom, c = 12.905 (3) Angstrom, beta = 1 02.72 (2)degrees, and V 1201.2 (5) Angstrom(3), Strontium and calcium ions were found to substitute for each other, The structure consists o f a network of alkaline-earth oxide polyhedra with broad channels para llel to the b axis, in which the bismuth ions reside. Two out of four crystallographically distinct Bi ions form infinite Bi-O zigzag ribbon s of edge-linked Bi-O units, while each of the other two form oxygen c orner-shared Bi-O chains along b. The lone pair electrons of the Bi io ns point toward each other in the channels.