The crystal structure of aramayoite Ag(Sb,Bi)S2*

Publisher Website
Google Scholar
Abstract
The crystal structure of aramyoite of the ideal composition Ag(Sb,Bi)S2 was determined using non-integrated photographic data. The cell dimensions are: a = 7.76 ± 0.02 Å, b = 8.85 ± 0.02 Å, c = 8.23 ± 0.02 Å, α = 100°11′ ± 15′, β = 90°43′ ± 15′, γ = 103°50′ ± 15′. The space group is P1. The final R value was 11.9% for 418 observed reflections.Aramayoite has a superstructure, and the substructure has a rocksalt-type arrangement. The structure is statistical, with partial and complete substitution of antimony atomic sites by bismuth. The unit-cell content is found to correspond with the formula unit Ag5Sb3.75Bi2S12 (valence rule is not fulfilled). There are three types of layers in the unit cell, an antimony-bismuth layer, a silver layer, and a mixed layer consisting of all three types of metal atoms.The mean bond distances are 2.55(8) Å for Ag–S, 2.66(8) Å for Sb–S and 2.77(7) Å for Bi–S.Aramayoite has a certain similarity with matildite, AgBiS2. Both are layer structures with pronounced cleavages. But in the case of matildite, the layers are alternate Ag, Bi, S, with metal layers in between sulfur layers. Both have distorted rocksalt-type substructures with statistical superstructures.

This publication has 0 references indexed in Scilit: