HAL will be down for maintenance from Friday, June 10 at 4pm through Monday, June 13 at 9am. More information
Skip to Main content Skip to Navigation
Journal articles

Crystal structure, XANES and charge distribution investigation of krennerite and sylvanite: analysis of Au—Te and Te—Te bonds in Au1–x Ag x Te2 group minerals

Abstract : The structure refinement and XANES study of two gold-silver-tellurides [Au 1+x Ag x Te 2 , krennerite (x = 0.11-0.13) and sylvanite (x = 0.29-0.31)] are presented and the structures are compared with the prototype structure of calaverite (x = 0.08-0.10). Whereas the latter is well known for being incommensurately modulated at ambient conditions, neither krennerite nor sylvanite present any modulation. This is attributed to the presence of relatively strong Te-Te bonds (bond distances < 2.9 A ˚) in the two minerals, which are absent in calaverite (bond distances > 3.2 A ˚). In both tellurides, trivalent gold occurs in slightly distorted square planar coordination, whereas monovalent gold, partly substituted by monovalent silver, presents a 2+2+2 coordination, corresponding to distorted rhombic bipyramids. The differentiation between bonding and non-bonding contacts is obtained by computation of the Effective Coordination Number (ECoN). The CHARge DIstribution (CHARDI) analysis is satisfactory for both tellurides but suggests that the Te-Te bond in the [Te 3 ] 2À anion is not entirely homopolar. Both tellurides can therefore be described as Madelung-type compounds, despite the presence of Te-Te in both structures.
Complete list of metadata

https://hal.univ-lorraine.fr/hal-03633784
Contributor : Massimo Nespolo Connect in order to contact the contributor
Submitted on : Thursday, April 7, 2022 - 11:31:51 AM
Last modification on : Friday, April 8, 2022 - 3:32:15 AM

File

Sylvanite-krennerite.pdf
Publisher files allowed on an open archive

Identifiers

Collections

Citation

Ginga Kitahara, Akira Yoshiasa, Makoto Tokuda, Massimo Nespolo, Hidetomo Hongu, et al.. Crystal structure, XANES and charge distribution investigation of krennerite and sylvanite: analysis of Au—Te and Te—Te bonds in Au1–x Ag x Te2 group minerals. Acta Crystallographica Section B : Structural Science, Crystal Engineering and Materials [2014-..], International Union of Crystallography, 2022, 78 (2), pp.117-132. ⟨10.1107/s2052520622000804⟩. ⟨hal-03633784⟩

Share

Metrics

Record views

8

Files downloads

5