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Structure of Pb‐rich chabournéite from Jas Roux, France
Author(s) -
Biagioni Cristian,
Moëlo Yves,
Favreau Georges,
Bourgoin Vincent,
Boulliard JeanClaude
Publication year - 2015
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520614028157
Subject(s) - triclinic crystal system , crystallography , crystal structure , electron microprobe , alternation (linguistics) , chemistry , bond length , materials science , mineralogy , linguistics , philosophy
The crystal structure of a specimen of `Pb‐rich' chabournéite from Jas Roux, Hautes‐Alpes, France, with the chemical formula obtained by electron microprobe analysis of Ag 0.04 (1) Tl 2.15 (2) Pb 0.64 (1) Sb 5.12 (1) As 5.05 (1) S 17.32 (5) , has been solved by X‐ray single‐crystal diffraction on the basis of 36 550 observed reflections (with F o > 4σ F o ) with a final R 1 = 0.074. Pb‐rich chabournéite is triclinic P 1, with unit‐cell parameters a = 8.5197 (4), b = 42.461 (2), c = 16.293 (8) Å, α = 83.351 (2), β = 90.958 (2), γ = 84.275 (2)°, V = 5823 (3) Å 3 . Its structural formula is close to [Tl 2 (Pb 0.8 Tl 0.1 Sb 1.1 )](Sb 4.1 As 4.9 )S 17 , with Z = 8. Its crystal structure is formed by the alternation of two pairs of slabs along the b axis, deriving from the SnS and PbS archetypes, respectively. 104 independent cation sites and 136 S sites occur in the unit cell. Slab interfaces show the alternation, along c , of Tl sites, ninefold coordinated, with Pb, Sb or mixed/split (Pb,Sb) and (Pb,Tl) sites. Within the slabs, 72 independent M 3+ sites ( M 3+ = As, Sb) occur. Considering M 3+ —S bond distances shorter than 2.70 Å, M S 3 triangular pyramidal groups are condensed according to various M m S n chain fragments (`polymers'). The solution of the crystal structure of chabournéite allows its comparison with the closely related homeotypes protochabournéite and dalnegroite.