The intergrowth structure of Ag1.2Bi17.6S23Cl8 and its relation to the tubular structure of Bi6+delta S6+3 delta O6-3 delta and the pavonite homologue Ag3xBi5-3xS8-6xCl6x-1

摘要

The crystal structures of two members of the solid solution series Bi6+delta S6+3 delta O6-3 delta and of Ag1.2Bi17.6S23O8 have been determined by single-crystal X-ray diffraction at room temperature. Single-crystals used for the investigations were obtained from a reaction involving Bi2S3 and AgCl in the molar ratio 3:2 at 740 K. Bi6+delta S6+3 delta Cl6-3 delta compounds crystallize in the hexagonal space group P6(3)/m (no. 176) with a = 11.427(2) angstrom, c = 4.071(1) angstrom, for delta = 0.64, and a = 11.540(2) angstrom, c = 4.040(1) angstrom, for delta = 0.86 (Z = 1). The disordered structure of Bi6+delta S6+3 delta O6-3 delta is closely related to the ordered rhombohedral structure of Bi4S5Cl2. It consists of parallel six-membered ring channels of face- and edge-sharing bicapped trigonal prisms around Bi atoms with additional Bi atoms on the central axes. Ag1.2Bi17.6S23Cl8 adopts the monoclinic space group C2/m (no. 12) with a = 53.036(9) angstrom, b = 4.030(1) angstrom, c = 11.643(4) angstrom, beta = 94.4(1)degrees, Z = 2. Ag1.2Bi17.6S23Cl8 adopts a new structure type that can be interpreted as a periodic layered intergrowth of modules from Bi6+delta S6+3 delta Cl6-3 delta and the pavonite homologue Ag3xBi5-3xS8-6xCl6x-1 (P-(2,P- x)) along [1 0 0]. The detailed geometrical analysis reveals a remarkable similarity of the interface in the three structures. (c) 2006 Elsevier Inc. All rights reserved.