Quaternary Silver Bismuth Chalcogenide Halides Ag - Bi - Q - X (Q = S, Se; X = Cl, Br): Syntheses and Crystal Structures

Systematic synthetic investigations of the quaternary systems Ag - Bi - Q - X (Q = S, Se; X = Cl, Br) led to a variety of quaternary phases that exhibit considerable structural diversity with increasing complexity. These include Ag1.2Bi17.6S23Cl8, AgBi4Se5Br3 and numerous members of the homologous double series Agx(N+1)Bi2+(1-x)(N+1)Q2+(2-2x)(N+1)X2+(2x-1)(N+1) denoted (N, x)P. N represents the order number of a given homologue and x is the degree of substitution of Bi by Ag with 1/2 <= x <= 1. Their structures are built up from two alternating types of modules denoted A and B that are stacked parallel to (001). In module A, rows of edge-sharing [MZ6] octahedra (Z = X and/or Q); M = Ag and/or Bi) running parallel to [010] alternate along [100] with parallel chains of paired monocapped trigonal prisms around Bi atoms. The module type denoted B represents NaCl-type fragments of varying thickness. It is defined by the number N of octahedra within the chain of edge-sharing octahedra running diagonally across it in the (010) plane of the structure. The thickness of module B for current members of the series extends from N = 0 to N = 7. All structures exhibit Ag/Bi disorder in octahedrally coordinated metal positions and Q/X (Q = S, Se; X = Cl, Br) mixed occupation of some anion positions. Some of these compounds are narrow gap semiconductors.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Technische Universität Dresden

Year

2004

Author dc:creator

• Poudeu Poudeu, Pierre Ferdinand

Contributors dc:contributor

• Ruck, Michael
• Pfitzner, Arno
• Grin, Yuri

• Bismut
• Silber
• Chalkogenide
• Halogenide
• Festlösung
• Kristallstrukturen
• Bismuth
• Silver
• Chalcogenide halides
• Solid solution
• Crystal structures