Homologous silver bismuth chalcogenide halides (N, x)P. III. The P-(4,P-x), P-(5,P- x), and P-(7,P- x) structure families of modular compounds with tunable composition and structure

Pierre Ferdinand P. Poudeu



2126 HH Dow

T: (734) 763-8436





Michael Ruck and Pierre F Poudeu Poudeu (2008)

Zeitschrift Fur Anorganische Und Allgemeine Chemie, 634(3):482-490.

The crystal structures of six members of the homologous series with general formula [BiQX](2)[Ag(x)Bi(1-x)Q(2-2x)X(2x)-1](N+1) (Q = S, Se; X = Cl, Br; 1/2 <= x <= 1) and N = 4 5, or 7 were determined by single-crystal X-ray diffraction. The series are characterized by the parameters N and x and are denoted P-(N,P- x). Ag3Bi4S6Cl3 (X = 0.60) (I), Ag3.5Bi3.5S5Br4 (x = 0.70) (II) and Ag3.65Bi3.35Se4.70Br4.30 (x = 0.73) (III) belong to P-(4,P- x) series Ag-5x Bi(7-5x)Q(12-10)x X 10(x-3) and adopt the AgBi6S9 structure type. The P-(5,P- x) compound Ag3.66Bi4.34S6.68Br3.32 (IV), which corresponds to x = 0.61 in Ag6xBi8-6xS14-12x Br12x-4, crystallizes isostructurally to AgBi3S5 center dot The compounds Ag4.56Bi5.44Se8.88Br3.12 (x = 0.57) (V) and Ag5.14Bi4.86S7.76Br4.24 (x = 0.64) (VI), which are members of P-(7,P- x) series Ag(8x)Bi(10-8x)Q(18-16x)Br(16x-6), adopt the Ag3Bi7S12 structure type. In the monoclinic crystal structures (space group C2/m) two kinds of layered modules alternate along [001]. Modules of type A uniformly consist of paired rods of face-sharing monocapped trigonal prisms around Bi atoms with octahedra around mixed occupied metal positions (M Ag/Bi) between them. Modules of type B are composed of [MZ(6)] octahedra, which are arranged in NaCl-type fragments of thickness N. All structures exhibit Ag/Bi disorder in octahedrally coordinated metal positions as well as Q/X mixed occupation of some anion positions. Corresponding to their black color, all compounds are narrow-gap semiconductors (E-g = 0.35 eV for (II)). General characteristics of the entire class of P(N- x) compounds are gathered in a catalogue.

Times Cited: 8

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