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Evain, M., Bindi, L. & Menchetti, S. (2006) Structure and phase transition of the Se-rich variety of antimonpearceite, [(Ag,Cu)(6)(Sb,As)(2)(S,Se)(7)]-[Ag9Cu(S,Se)(2)Se-2]. Acta Crystallogr. Sect. B-Struct. Sci. 62 768–774.
Added by: Florent Boucher (2016-05-12 13:21:36) |
| Type de référence: Article DOI: 10.1107/S0108768106022798 Numéro d'identification (ISBN etc.): 0108-7681 Clé BibTeX: Evain2006 Voir tous les détails bibliographiques  |
Catégories: MIOPS Mots-clés: coordination, pearceite, polybasite, series, silver, single-crystal structure Créateurs: Bindi, Evain, Menchetti Collection: Acta Crystallogr. Sect. B-Struct. Sci. |
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| Résumé |
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The crystal structure of a Se-rich antimonpearceite has been solved and refined by means of X-ray diffraction data collected at temperatures above ( room temperature) and below ( 120 K) an ionic conductivity-induced phase transition. Both structure arrangements consist of the stacking of [(Ag, Cu)(6)(Sb, As)(2)(S, Se)(7)](2-) A (A') and [Ag9Cu(S, Se)(2)Se-2](2+) B (B') module layers in which Sb forms isolated SbS3 pyramids typically occurring in sulfosalts; copper links two S atoms in a linear coordination, and silver occupies sites with coordination ranging from quasi-linear to almost tetrahedral. In the ionic-conducting form, at room temperature, the silver d(10) ions are found in the B (B') module layer along two-dimensional diffusion paths and their electron densities described by means of a combination of a Gram-Charlier development of the atomic displacement factors and a split-atom model. The structure resembles that of pearceite, except for the presence of both specific (Se) and mixed (S, Se) sites. In the low-temperature 'ordered' phase at 120 K the silver d(10) ions of the B (B') module layer are located in well defined sites with mixed S-Se coordination ranging from quasi-linear to almost tetrahedral. The structure is then similar to that of 222-pearceite but with major differences, specifically its cell metric, symmetry and local arrangement in the B (B') module layer.
Added by: Florent Boucher |